They break bzr-git, and bzr-git breaks the Minetest PPAs.

Previously, race conditions occurred inside logging, that caused
segfaults because a thread was trying to use an old pointer that
was freed when the string was reallocated. Using a fixed-length buffer
avoids this, at the cost of cutting too long messages over seveal lines.

The shadow bug at y = 63 was caused by dark air being placed as dust,
when the biome dust was unspecified it was falling back to 'air'
In dustTopNodes only dust == 'ignore' will disable dust placement

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

replaces #4003

Previous mountain terrain generation was by necessity placing
stone in air, this was removing air from any overgenerated
structures such as tunnels, dungeons and large caves
Moving it into the base terrain generation loop ensures that
only 'ignore' is replaced

generateRidgeTerrain: only return if node_max.Y < water_level - 16
Previously, if water level was set a few nodes above a mapchunk
border the river channel was only partially excavated

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.

Place biome top node on tunnel entrance floor
Instead of doing nothing at node_max.Y + 1 use 1-down
overgeneration for tunnel generation and noisemaps

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