The fallback vector is in case 'wallmounted to dir' is nil due
to voxelmanip placing a wallmounted node without resetting a
pre-existing param2 value that is out-of-range for wallmounted.
The fallback vector corresponds to param2 = 0.

Adds a flag to forceload_block which lets you turn off persistence for
that forceload.

Add 'core.LIGHT_MAX = 14' to builtin/game/constants.lua with the intention
to replace misplaced 'default.LIGHT_MAX = 14' in Minetest Game.
Add comment in light.h requiring the constant be changed in both places.
Add lighting bug warning to note in lua_api.txt.
There are hundreds of mod uses of 15 which causes a lighting bug.

Prevents duplicate names: 'NickName', 'nickname', 'NICKNAME'.
Skips already registered users, so they can connect as usual.

core.check_player_privs accepts as first argument a name or player object, but just tested for a string.
This caused crashes inside builtin, when being passed any unexpected types.

This provides a better (duck-typing like) test, better error reporting.

Use the setting "profiler.load" to enable profiling.
Other settings can be found in settingtypes.txt.

* /profiler print [filter] - report statistics to in-game console
* /profiler dump [filter] - report statistics to STDOUT and debug.txt
* /profiler save [format [filter]] - saves statistics to a file in your worldpath
	* txt (default) - same treetable format as used by the dump and print commands
	* csv - ready for spreadsheet import
	* json - useful for adhoc D3 visualizations
	* json_pretty - line wrapped and intended json for humans
	* lua - serialized lua table of the profile-data, for adhoc scripts
* /profiler reset - reset all gathered profile data.
	This can be helpful to discard of any startup measurements that often spike during loading or to get more useful min-values.

[filter] allows limiting the output of the data via substring/pattern matching against the modname.

Note: Serialized data structures might be subject to change with changed or added measurements.
	csv might be the most stable, due to flat structure.

Changes to the previous version include:

* Updated and extended API monitoring
* Correct calculation of average (mean) values (undistorted by idleness)
* Reduce instrumentation overhead.
* Fix crashes related to missing parameters for the future and occasional DIV/0's.
* Prevent issues caused by timetravel (overflow, timejump, NTP corrections)
* Prevent modname clashes with internal names.
* Measure each instrumentation individually and label based on registration order.
* Labeling of ABM's and LBM's for easier classification.
  Giving several ABM's or LBM's the same label will treat them as one.
  Missing labels will be autogenerated based on name or registration order.
* Configurable instrumentation and reporting. Skip e.g. builtin if you don't need it.
* Profile the profiler to measure instrumentation overhead.

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.

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

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.

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.

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.
```

This privilege allows map protection bypassing for server operators
and world moderators.

Initially I had thought that bypassing protection mods would have been
something that could entirely be done inside mods and minetest_game,
but the concept of protection is defined in core, in the code of
core.is_protected().

I don't feel that it would be logical to introduce a protection
concept in core, but not some way around that for server operators
to maintain map parts that need fixing, de-griefing or cleanup.

Others had noticed the same problems, and proposed a patch to
minetest_game. That patch is fine by itself, but it fails to add
protection bypass functionality for digging normal nodes and placing
nodes.

So, instead, we indroduce the new priv "protection_bypass" in core,
and modify 'on_place_node' and 'node_dig' to allow bypassing node
protections if the player holds this priv.

This priv was tested with protector redo by tenplus1.

A followup patch to Minetest Game will include allowing special checks
for doors, trapdoors, chests in Minetest Game.

Protection mods will likely want to mimic the changes in their relevant
code sections.

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.

This allows mods to perform both asynchronous and synchronous HTTP
requests. Mods are only granted access to HTTP APIs if either mod
security is disabled or if they are whitelisted in any of the
the secure.http_mods and secure.trusted_mods settings.

Adds httpfetch_caller_alloc_secure to generate random, non-predictable
caller IDs so that lua mods cannot spy on each others HTTP queries.

This makes the functions a bit faster since they don't
have to recreate the tables every invocation, and makes
the code more readable.

Also, document `wallmounted_to_dir`.

The function was implemented but not documented in `lua_api.txt`.