Mgv6: Enable snowbiomes by default. Double biome noise spread. 3 octaves, 0.5 persistence for humidity

Due to compatibility concerns, this is temporarily disabled.

  * Combine client and server man pages.
  * Update unit test options and available databases in man page.
  * Add `--worldname` to man page.
  * Fix a bunch of places where `"Minetest"` was used directly instead of `PROJECT_NAME`.
  * Disable server build by default on all operating systems.
  * Make `ENABLE_FREETYPE` not fail if FreeType isn't found.
  * Enable LevelDB, Redis, and FreeType detection by default.
  * Remove the `VERSION_PATCH_ORIG` hack.
  * Add option to search for and use system JSONCPP.
  * Remove broken LuaJIT version detection.
  * Rename `DISABLE_LUAJIT` to `ENABLE_LUAJIT`.
  * Rename `minetest_*` variables in `version.{h,cpp}` to `g_*`.
  * Clean up style of CMake files.

This feature is still experimental and has some issues. Also,
increase texture_min_size to 64 px. The setting was initially
a conservative 16 so that the effect would not be noticable
for players who aren't using aniso/bi/trilinear filtering. This
isn't necessary now that texture_clean_transparent is disabled
by default.

Signed off by: Zeno, kwolekr

Revert "Switch default scaling factor to 0.75 as most ppl seem to have 96dpi screens instead of previous assumed 72"
which ain't required any longer as fonts are no longer autoadjusted
This reverts commit 7ad17a25.

Split gui_scaling to gui_scaling + hud_scaling as those elements need different handling on some devices

Switch default scaling factor to 0.75 as most ppl seem to have 96dpi screens instead of previous assumed 72

If liquid_queue_purge_time == 0 then disable the queue size limiting and make this the default setting
Additionally, liquid_loop_max now defaults to 100000

Fix non coding style conforming glb_fontengine to g_fontengine
Fix fonts never been deleted due to grabbed to often

Signed-off-by: Craig Robbins <kde.psych@gmail.com>

Signed-off-by: Craig Robbins <kde.psych@gmail.com>

Since minetest has no mobs within the core anymore, I suppose these
settings and code should go. Any mod that uses `minetest.setting_getbool`
will work with no problem since the default return value is `false`.

This can delay connections by several minutes.

There have been plenty of ppl involved in creating this version.
I don't wanna mention names as I'm sure I'd forget someone so I
just tell where help has been done:
- The partial android versions done by various ppl
- Testing on different android devices
- reviewing code (especially the in core changes)
- testing controls
- reviewing texts

A big thank you to everyone helping this to be completed!