Deprecate get_look / set_look pitch / yaw

- Generalise node names to c_wall and c_alt_wall
- Remove 'mossratio' and instead disable alt_wall loop if
  c_alt_wall == CONTENT_IGNORE
- Use one generalised 3D noise for alternative wall nodes and in
  mgv6 create moss distribution similar to the previous

- Rename rarity noise to density noise and enable the option of multiple
  dungeons per chunk determined by the value. Recreate previous distribution
- Add parameters for min and max rooms per dungeon
- Add dungeon y limits

- Integrate river water properly

Generalisation is needed now that we have sandstone and desert stone
dungeons by default and can choose any node for alternative structure.
The current code is based around cobble dungeons with mossycobble
alternative nodes, the 2 noises controlling the alternative nodes
are based on wetness.

Enabling multiple dungeons per chunk with definable number of rooms
allows the option of very dense and complex underground structures
that could interconnect to create megastructures.
Y limits are added to be consistent with other mapgen elements, and
enable locaton of dungeon or megastructure realms as part of our
'stacked realms' philosophy.

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.

Texture packs have no way to know what nodes are available, so this shouldn't be a error message.

 - Fix unused c_sand member warning in Valleys Mapgen
 - Fix some code style
 - Make some std::string params const ref

Thanks to @Wayward1 for reporting the bug.

Fixes #4212.

Add new colours 'skycolour_bright_night', 'bgcolour_bright_night'
and enable these between sunset end and sunrise start
Night sky has same hue as day sky but is darker and more saturated
Night horizon haze (bgcolour) is slightly less saturated and
slightly brighter than night sky, to be consistent with daytime
horizon haze

Top of texture no longer shows above horizon during night and day

Mgvalleys: Remove riverbed sand placement from base terrain generation
Riverbed material placement moved to MapgenBasic::generateBiomes()
Document fields and add note that the biome API is still unstable

- Adds only ~100 nodes per chunk to trans_liquid with similar processing time
- Adds liquid nodes themselves instead of potential solid nodes below them
- CONTENT_IGNORE nodes are interpreted as if they continue their neighborhood
- This allows liquid columns to span multiple chunks without being interrupted
- NOTE: Expects an one-node border in generation chunk without liquid changes

This fixes value truncation (and therefore incompatibility) on platforms
with an LP32 data model, such as VAX or MS-DOS.

Adds initial ingame gamepad support to minetest.

Full Formspec support is not implemented yet and
can be added by a later change.

* Move key types into own file
* Use Generalized input methods in game.cpp

Previously, rivers were sometimes blocked by vertical walls
of mountain terrain due to river carving being disabled
when base terrain height was below water_level - 16
Remove now unused base terrain heightmap created in
generateTerrain()

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/

Currently translated at 7.8% (70 of 887 strings)

Currently translated at 57.2% (508 of 887 strings)

Currently translated at 100.0% (887 of 887 strings)

Currently translated at 39.3% (349 of 887 strings)

Currently translated at 57.0% (506 of 887 strings)

This is a merger of three commits.

Currently translated at 57.1% (507 of 887 strings)

Currently translated at 100.0% (887 of 887 strings)

Gives a convenient way to check a player's password.

This entirely bypasses the SRP protocol, so should be used
with great care.

This function is not intended to be used
in-game, but solely by external protocols, where no
authentication of the minetest engine is provided, and
also only for protocols, in which the user already gives the
server the plaintext password.

Examples for good use are the classical http form, or irc,
an example for a bad use is a password change dialog inside
formspec.

Users should be aware that they lose the advantages of the SRP
protocol if they enter their passwords for servers outside the
normal entry box, like in in-game formspec menus,
or through irc /msg s,

This patch also fixes an auth.h mistake which has mixed up the
order of params inside the decode_srp_verifier_and_salt function.

Zeno-: Added errorstream message for invalid format when I committed

Note that the macro CHECK_FILE_ERR implements the code removed

Adds the particle option `collision_removal = bool`

Some particles are hard to use right now since they either go through
solid blocks (without collision detection), and with collision
detection enabled they (e.g. raindrops) would just stop dead on the
floor and sit there until they expire, or worse, scrape along a wall
or ceiling.

We can solve the problem by adding a boolean flag that tells the
particle to be removed if it ever collides with something. This will
make it easier to add rain that doesn't fall through your roof or stick
on the top of it. Or clouds and smoke that don't go through trees.

Particles that collide with this flag are marked expired
unconditionally, causing them to be treated like normal expired
particles and cleaned up normally.

Documentation is adjusted accordingly.

An added bonus of this patch is that particles can potentially collide
many times with nodes, and this reduces the amount of collisions to 1
(max), which may end up reducing particle load on the client.