Fix use of 'air_above' bool so that biome
nodes are only placed in tunnel floors
Minor code improvements
'Continue' when massive cave air is placed

@kilbith spotted correctly that I had accidentally removed the
"soft" edging on the minimap overlay by converting it from RGBA
to Indexed, which killed the transparent pixels on the edging.

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.

Backports 10 commits, with 8 commits
actually affecting source code:

https://github.com/est31/csrp-gmp/compare/695822e45d9ca48b75b4ec1af1b4eea19139f8b1...deaa11a7c29a730087380da231e785909ad21630

Document hpchange callback ordering thing

Callbacks registered by register_on_player_hpchange are ordered so that non-modifiers are called after modifiers are called. Credit to @TeTpaAka who mentioned this previously-undocumented feature in #3799.

See also commit

aa13baa3 "Add minetest.register_on_player_hpchange"

Related: #3730

This adds a simple, and small "North" indicator to the circular
minimap. The indicator is in a classical triangle-like arrow with a
little bit of shading to accentuate the shape and give it a little
bit depth. The indicator is stuck exactly at the edge as far outwards
as possible, and is not too intrusive but still easy enough to spot.

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

Arch Linux doesn't put it's ncursesw includes inside an ncursesw
directory.  This script ends up setting USE_CURSES as true, but
doesn't pick up any of the headers.

https://bugs.archlinux.org/task/13994

Instead of doing nothing at node_max.Y + 1 use 1-down
overgeneration for tunnel generation and noisemaps
Move some old unused code in mgv7 to end of file

It was caused by player not moving because fall was prevented, but their
velocity still increasing, causing fatal fall damage when world was
finally loaded. This commit fixes it by setting player velocity to zero
when the world around them is not loaded.

Fix warnings added by commit 01ae43c4

Fixes #3952

Also, rework the colorizing code to be more efficient.

Commit

c3b27975 "Move object nametags to camera"

has added a regression to still display
a shadow if their alpha got set to 0.

Additionally, fix misc. code style issues

Use a proper switch with breaks.

* Fix leak like behaviour if you load multiple schematics in a loop.

* Cleanup check in for, fixing theoretical out of bounds read if
	Schematic::deserializeFromMts reduced the number of elements
	in m_nodenames. A != check may need an overflow of the counter
	before it hits, if origsize is larger than m_nodenames.size().

* Fix function name passed to errorstream: it was wrong. Also use
	__FUNCTION__ instead of manually using the method name at other
	places in the function.

* Don't shadow the name member in the loop.

This fixes #3935, a regression from 0338c2eb.
An 'optimization' was performed where an index for the VoxelManip being
operated on was mistakenly used for bounds checking within the incorrect
VoxelArea, namely, the area wherein light should be spread.

Fix initialisation of variable 'disp'
Fix a few minor code style issues
Add independent X motion combining 2 prime frequencies

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>

Writing an u8 to verbosestream writes a char, not it's numeric value.

This reverts commit 25da0594.

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.

Currently translated at 34.5% (299 of 865 strings)

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