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.

Missing `valleys` in `settingtypes.txt` and `minetest.conf.example`.

* Update OpenSSL (thanks @sapier, i use his patch!), Curl and SQLite3.
* Remove old arm config. Almost all phones that use ARMv5 have 1 core and 256-512 RAM, it's about 2-5 FPS.
* Do -O3 optimization for libs and remove -fexpensive-optimizations for Minetest (-O3 includes this! Read gcc docs).
* OpenSSL fix - thanks @sapier, again.

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.

Fixed a minor mistake that made it appear as if the inventory
is serialized multiple times - once per each variable. In fact
it is serialized once per each node.

This reverts commit 60dc01dc.

This fixes issue #3773

Having a non-power-of-two image broke the Android app.

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.

If the default value of a setting was empty,
it previously generated a trailing space.

Currently translated at 61.3% (483 of 787 strings)

(Merger of five commits)

Currently translated at 49.5% (390 of 787 strings)

(Merger of three commits)

Currently translated at 47.0% (370 of 787 strings)

(Merger of two commits from the same author)

Currently translated at 37.3% (294 of 787 strings)