Allow mods such as protection mods to over ride on_rightclick.
Usecase is creating shared doors without the need for keys.

No longer use default_wood.png for one side of the bed head and
one side of the bed bottom node.
Add a new texture for the underside of both beds.

Fixes most z-fighting caused by underwater nodeboxes.
Special tiles were for 'new style water' (lowered water level) which was
removed a few years ago.

Fix slabs combining into a cube: Facedir is only set for the cube if it has
paramtype2 = "facedir". This avoids liquid appearing in connected
framed glasslike.

All stair/slab nodes with parent nodes that are rotatable (wood and bricks)
are reverted to not having world-aligned textures, to fix the breakage of
rotated stair/slab appearence in worlds.

Update, and add missing documentation to, game_api.txt.

Fence rail: Only connect to 'group:fence'.
Update map mod README crafting recipe documentation.

Before, it checked if the node name *contained* "stairs:slab_", which could detect
things like "xxxxxstairs:slab_xxxx". Changed the pattern to "^stairs:slab_".

Precisely reduce trees and logs per mapchunk division to compensate.

sfinv:
Move license information to create the missing license.txt file.
Make README consistent with other Minetest Game mods.

player_api:
Add missing texture and sound credits to README.
Update and add extra license information.

default:
Remove credit for 'player_damage.ogg' sound.

Previously, maximum flora density was chosen based on the extremely rare
occurrence of all 8 flowers being at high density at one location. This
caused flora everywhere to spread to an unacceptably high density.

Revert the threshold to 3, which in testing results in a more acceptable
maximum density of 7 flora per 9x9 area.