Reduce spread from 96 to primes 61 and 67 (either side of 64)
Prime spreads help to keep 3D noise periodic features unaligned
'cave width' 0.2 to preserve tunnel width
Reduce octaves to 3 to improve network structure

This allows a nodedef to specify a fixed value for param2 to be
used for all normal placements.

There are several uses for this:

- nodes that require param2 to be set to a non-zero value for
  internal mod use. E.g. leafdecay could use this to detect that
  leaves are played by players.
- force wallmounted or facedir value at placement at placement

This overrides any player look direction or other on-the-fly
param2 setting during placement.

Adds initial ingame gamepad support to minetest.

Full Formspec support is not implemented yet and
can be added by a later change.

Add documentation, move files to a proper place and avoid memory leaks.
Make it work with most kind of texts, and allow backgrounds too.

Colored chat working as expected for both freetype and non-freetype builds. @nerzhul improvements * Add unit tests * Fix coding style * move guiChatConsole.hpp to client/

Partially reverts #3547
Infotext remains optional for objects, empty by default

Fixes #4120.

The change keys dialog can't be left. It doesn't make
much sense to show it on Android in the first place,
therefore disable it, just like commit

aed70cb0 'Disable sound and key binding settings in "pause" menu on android'

has disabled it for the esc menu.

Fixes #4115.

Bug and whitespace error fixed (Zeno)

Correct parameter names mg_valleys to mgvalleys
Remove biome NoiseParams from MapgenValleysParams
Improve format of parameter code

Also, fix a nil error that can happen sometimes in
menu_handle_key_up_down

This fixes the problem that the first timer tick is an
overrun and causes all timers to expire immediately.

replaces #4003

This seems very little cost and matches the old behavior more
closely. This will cause some more falling nodes to get added
to falling clusters. With the efficiency of the algorithm, this
really doesn't do much damage.

@SmallJoker has noted a bug that servers from the (local) main menu
favorites list can't be opened.

This commit fixes the bug by disabling any main menu based protocol
checks for servers from the favorite list.

Also, it fixes a second bug that happens when a server from the
public serverlist doesn't send its supported protocol versions,
most likely because its running a minetest older than commit [1].
Then we have shown an error msg that the server has enforced
one specific protocol version. This was most likely not the case.

Of course, we can't do anything better than do an assumption on
the protocol versions if they are not known. That assumption
should however be closest to the most often occuring case as
possible.

Also, some little cleanups.

[1]: 5a0ed780 "Server: announce MIN/MAX protocol version supported to serverlist. Client: check serverlist"

Apply de morgan to simplify the logic.

Setting only loaded once, default value is to enable them.

This took me a while to figure out. We no longer visit all 9 block
around and with the touched node, but instead visit adjacent plus
self. We then walk -non- recursively through all neigbors and if
they cause a nodeupdate, we just keep walking until it ends. On
the way back we prune the tail.

I've tested this with 8000+ sand nodes. Video result is here:

  https://youtu.be/liKKgLefhFQ

Took ~ 10 seconds to process and return to normal.

 - Use local variables for tabs in place of globals
 - Merge together if statements where possible
 - Replace manual table searching code with indexof where possible

Additionally, fix misc. code style issues

2016-03-27 15:47:01: ERROR[Main]: ServerError: Lua: Runtime error from mod '*builtin*' in callback luaentity_Step(): Node name is not set or is not a string!
2016-03-27 15:47:01: ERROR[Main]: stack traceback:
2016-03-27 15:47:01: ERROR[Main]: 	[C]: in function 'add_node'
2016-03-27 15:47:01: ERROR[Main]: 	/usr/share/minetest/builtin/game/falling.lua:96: in function </usr/share/minetest/builtin/game/falling.lua:43>

Commit

65c09a96 "Set acceleration only once in falling node"

has made the acceleration being set only once.
But this has introduced a regression.

Fix #3884.

Undoubtably this may cause problems later if unchecked.

```
2016-03-22 21:57:52: WARNING[Server]: Assignment to undeclared global "options" inside a function at .../sofar/git/minetest/bin/../builtin/game/chatcommands.lua:862.
```

ABM's are hardcoded to run every 1.0s, NodeTimers are hard coded to
run at every 1.0s. Block mgmt is running every 2.0sec.

However, these timers can be better tuned for both higher and lower
values by server owners. Some server owners want to, and have the
resources to send more packets per second to clients, and so they
may wish to send smaller updates sooner. Right now all ABM's are
coalesced into 1.0 second intervals, resulting in large send queues
to all clients. By reducing the amount of possible timers, one can
get a far better response rate and lower the perception of lag.

On the other side of the camp, some servers may want to increase
these values, which again isn't easily doable.

The global settings abm_interval and nodetimer_interval are set to
current values by default. I've tested with 0.2/0.5 type values
and noticed a greatly improved response and better scattering of
nodetimers, as well as enjoying not faceplanting into doors with
pressure plates anymore.

The legacy init packet (pre v25) sends information about the client's
password that a server could use to log in to other servers if the
username and password are the same. All the other benefits of SRP of
protocol v25 are missed if the legacy init packet is still sent during
connection creation.

This patch adds an option to not send the v25 init packet. Not sending
the v25 packet means breaking compat with pre v25 servers, but as the
option is not enabled by default, no servers are affected unless the
user explicitly flips the switch. More than 90% of the servers on the
serverlist support post v25 protocols.

The patch also fixes a bug with greying out of non compliant servers
being done wrongly, the min and max params were mixed.