Fixes #4579, a regression introduced by commit

d4c76258 "Chat: new settings to prevent spam"

This is part 2 for 5f084cd9

Other improvements:

* Use the defined ItemGroupList when used
* make Client::checkPrivilege const
* inline some trivial functions
* Add ActiveObjectMap typedef
* Add SettingsEntries typedef

Added the following chat coreside features
* Chat messages length limit
* Message rate limiting
* Message rate kicking

Note:
* handleChat now takes RemotePlayer pointer instead of u16 to remove useless
  lookups

This commit refactors the majority of the Mapgen settings system.
- MapgenParams is now owned by MapSettingsManager, itself a part of ServerMap,
  instead of the EmergeManager.
- New Script API functions added:
    core.get_mapgen_setting
    core.get_mapgen_setting_noiseparams,
    core.set_mapgen_setting, and
    core.set_mapgen_setting_noiseparams.
- minetest.get/set_mapgen_params are deprecated by the above new functions.
- It is now possible to view and modify any arbitrary mapgen setting from a mod,
  rather than the base MapgenParams structure.
- MapgenSpecificParams has been removed.

Adds the particle option `collision_removal = bool`

Some particles are hard to use right now since they either go through
solid blocks (without collision detection), and with collision
detection enabled they (e.g. raindrops) would just stop dead on the
floor and sit there until they expire, or worse, scrape along a wall
or ceiling.

We can solve the problem by adding a boolean flag that tells the
particle to be removed if it ever collides with something. This will
make it easier to add rain that doesn't fall through your roof or stick
on the top of it. Or clouds and smoke that don't go through trees.

Particles that collide with this flag are marked expired
unconditionally, causing them to be treated like normal expired
particles and cleaned up normally.

Documentation is adjusted accordingly.

An added bonus of this patch is that particles can potentially collide
many times with nodes, and this reduces the amount of collisions to 1
(max), which may end up reducing particle load on the client.

Rebased by Zeno (2016-04-2016)

We introduce a new nodebox type "connected", and allow these nodes to
have optional nodeboxes that connect it to other connecting nodeboxes.

This is all done at scenedraw time in the client. The client will
inspect the surrounding nodes and if they are to be connected to,
it will draw the appropriate connecting nodeboxes to make those
connections.

In the node_box definition, we have to specify separate nodeboxes for
each valid connection. This allows us to make nodes that connect only
horizontally (the common case) by providing optional nodeboxes for +x,
-x, +z, -z directions. Or this allows us to make wires that can connect
up and down, by providing nodeboxes that connect it up and down (+y,
-y) as well.

The optional nodeboxes can be arrays. They are named "connect_top,
"connect_bottom", "connect_front", "connect_left", "connect_back" and
"connect_right". Here, "front" means the south facing side of the node
that has facedir = 0.

Additionally, a "fixed" nodebox list present will always be drawn,
so one can make a central post, for instance. This "fixed" nodebox
can be omitted, or it can be an array of nodeboxes.

Collision boxes are also updated in exactly the same fashion, which
allows you to walk over the upper extremities of the individual
node boxes, or stand really close to them. You can also walk up
node noxes that are small in height, all as expected, and unlike the
NDT_FENCELIKE nodes.

I've posted a screenshot demonstrating the flexibility at
    http://i.imgur.com/zaJq8jo.png
In the screenshot, all connecting nodes are of this new subtype.

Transparent textures render incorrectly, Which I don't think is
related to this text, as other nodeboxes also have issues with this.

A protocol bump is performed in order to be able to send older clients
a nodeblock that is usable for them. In order to avoid abuse of users
we send older clients a "full-size" node, so that it's impossible for
them to try and walk through a fence or wall that's created in this
fashion. This was tested with a pre-bump client connected against a
server running the new protocol.

These nodes connect to other nodes, and you can select which ones
those are by specifying node names (or group names) in the
connects_to string array:
      connects_to = { "group:fence", "default:wood" }
By default, nodes do not connect to anything, allowing you to create
nodes that always have to be paired in order to connect. lua_api.txt
is updated to reflect the extension to the node_box API.

Example lua code needed to generate these nodes can be found here:
    https://gist.github.com/sofar/b381c8c192c8e53e6062

Since commit

3b50b276 "Optional reconnect functionality"

there is a config option named ask_reconnect_on_crash.
It asks the client to reconnect to the server if the server crashed.
It has been implemeted and works, but due to a function parameter not
being passed it never showed effect. This patch adds the parameter
and fixes the bug.

Also fixes the `reconnect` option of minetest.request_shutdown being ignored.

To avoid spawn search failing in new specialised mapgens
Increase spawn search range to 4000 nodes
Add getSpawnLevelAtPoint() functions to EmergeManager, class Mapgen
and all mapgens
Remove getGroundLevelAtPoint() functions from all mapgens except mgv6
(possibly to be re-added later in the correct form to return actual
ground level)
Make mgvalleys flag names consistent with other mapgens
Remove now unused 'vertical spawn range' setting

Fixes bug for which commit

6c37e89f "Fix old client showing duplicated health bar on new server"
by @sapier

laid the groundwork, where the server has
updated its copy of the hud flags without
respecting the mask.

Fixes #3395.

Fix regression of commit

5e507c98 "Add server side ncurses terminal"

which allowed all players, even those without a shout priv, to chat.

Fixes #3362.

Comply with line limit.

Fix regression of commit

5e507c98 "Add server side ncurses terminal"

where no line termination character was printed after a
lua print outside of terminal mode.

Fixes #3350.

This adds a chat console the server owner can use for administration
or to talk with players.
It runs in its own thread, which makes the user interface immune to
the server's lag, behaving just like a client, except timeout.
As it uses the same console code as the f10 console, things like nick
completion or a scroll buffer basically come for free.
The terminal itself is written in a general way so that adding a
client version later on is just about implementing an interface.

Fatal errors are printed after the console exists and the ncurses
terminal buffer gets cleaned up with endwin(), so that the error still
remains visible.

The server owner can chose their username their entered text will
have in chat and where players can send PMs to.
Once the username is secured with a password to prevent anybody to
take over the server, the owner can execute admin tasks over the
console.

This change includes a contribution by @kahrl who has improved ncurses
library detection.

It isn't possible to use atomic operations for floats, so don't use them there.

Having a lock is good out of other reasons too, because this way the float time
and the integer time both match, and can't get different values in a race,
e.g. when two setTimeofDay() get executed simultaneously.

Previously, the server called FATAL_ERROR when a Lua error occured.
This caused a (mostly useless) core dump.
The server now simply throws an exception, which is caught and printed before
exiting with a non-zero return value.
This also fixes a number of instances where errors were logged multiple times.

Increase default from 6 to 16 to help with mgv7 and mgfractal
Large-scale or alternative mapgens can result in a lowland spawn point not
being found, causing a spawn at (0, 0, 0) possibly buried underground
The max height is now settable to allow correct player spawn
in any mapgen or when using custom noise parameters

-> Put access to time variables under the time lock.
-> Merge both time locks, there is no point to have two locks.
-> Fix the lock being released too early in Environment::setTimeOfDay
-> Add serverside getter so that you don't have to get
	the environment if you only have the server

These names are reserved for the compiler/library implementations.

Remove DTIME macro and its uses, too

1. Check for entity addition success in spawn_item implementation
2. Check for success in item_drop callback, so that the player
doesn't lose the item if they are outside bounds and try to drop it.
3. When existing player joins game, check that their position is inside
map bounds. If not, set their position to the return value of findSpawnPos().
4. Make findSpawnPos() respect the border

2 fixes a lua crash if a player drops an item outside map bounds.
3 fixes an assertion crash if a player leaves when being outside map bounds,
and then rejoins.

Use std::queue instead of std::set, we don't need such a heavy container.
Don't convert position to int to convert it back to float in the next function.

The legacy code added in commit

d879a539 - "Add minetest.swap_node"

for sending the whole mapblock to older clients on the case of a node
modification with swap_node, had the problem that the block chosen to be
sent to the client was referenced with node coordinates and not with
block coordinates, resulting in getting the wrong block sent to the client.

  * Rename everything.
    * Strip J prefix.
    * Change UpperCamelCase functions to lowerCamelCase.
  * Remove global (!) semaphore count mutex on OSX.
  * Remove semaphore count getter (unused, unsafe, depended on internal
    API functions on Windows, and used a hack on OSX).
  * Add `Atomic<type>`.
  * Make `Thread` handle thread names.
  * Add support for C++11 multi-threading.
  * Combine pthread and win32 sources.
  * Remove `ThreadStarted` (unused, unneeded).
  * Move some includes from the headers to the sources.
  * Move all of `Event` into its header (allows inlining with no new includes).
  * Make `Event` use `Semaphore` (except on Windows).
  * Move some porting functions into `Thread`.
  * Integrate logging with `Thread`.
  * Add threading test.

src/server.cpp
src/emerge.cpp

-> Remove the SendableMediaAnnouncement struct
-> Forge the packet directly in the m_media loop, spare one loop and the construction of a vector
-> Use preincrement to spare iterator copies

Enable the server to request the client to reconnect.

This can be done with the now extended minetest.request_shutdown([reason], [reconnect]) setting.