NDT_CONNECTED attempts to connect to any side of nodes that it can
connect to, which is troublesome for FACEDIR type nodes that generally
may only have one usable face, and can be rotated.

We introduce a node parameter `connect_sides` that is valid for
any node type. If specified, it lists faces of the node (in "top",
"bottom", "front", "left", "back", "right", form, as array) that
connecting nodeboxes can connect to. "front" corresponds to the south
facing side of a node with facedir = 0.

If the node is rotatable using *simple* FACEDIR, then the attached
face is properly rotated before checking. This allows e.g. a chest
to be attached to only from the rear side.

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

The MainMenuManager set the console invisible when a
formspec opened over it, but didn't properly close it,
and the chat console never set itself visible again.

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.

We can just test for the presence of these settings nicely here,
no need to use a try / catch construct.

I've written several experimental bits of code that revolve around the
need for a consistent calendar, but implementing one is extremely hard
in mods due to time changes and mods overriding core.get_timeofday(),
which will conflict.

The second part of the problem is that doing this from a mod requires
constant maintenance of a settings file.

An implementation in core is trivial, however, and solves all of
these problems at virtually no cost: No extra branches in server
steps, and a single branch when minetest.set_time_of_day(), which is
entirely reasonable.

We store the day_count value in env_meta.txt.

The use case is obvious: This change allows mods to create an actual
virtual calendar, or properly account for seasonal changes, etc..

We add a "/days" chatcommand that displays the current day count. No
permissions are needed. It can only retrieve the day count, not
modify it.

* Replace string by-val passing with const reference
* Fix code style
* Remove redundant `int table` definition and indentation level

Throwing a LuaError calls destructors as it propagates up the stack,
wheres lua_error just executes a longjmp.

Increase maximum spawn altitude to reduce spawn issues.

Fixes #3764

This function could be used to steal insecure environments from trusted mods.

This still only supports 256 characters, but that's because
Irrlicht's clipboard handlers don't support wide characters.

keymap_console opens a full window for chat history browsing.

This reverts commit 60dc01dc.

This fixes issue #3773

Lower water table where base humidity is low.
Alter heat and humidity to compensate for river humidity and altitude
chill.
Correct misuse of surface_max_y in generateTerrain.
Remove sand trails in the water at river mouths.
Remove river water below water_level.
Correct heat/humidity calculations where noises are less than zero.
Correct heightmap errors as much as possible.
Make humidity calculations more readable.

Fixes #3765

In the calculation of y_start,
when 'column height max' was large it caused
nmin.Y + max_height > nmax.Y - max_height
Now, in this situation y_start is set to the
midpoint between nmin.Y and nmax.Y

Limit y0 and y1 to between nmin.Y and nmax.Y,
otherwise index calculation, which has no checks for limits,
places them at unwanted locations in the voxelmanip