Removing the node above was an error and is unnecessary

This makes register_trapdoor act the same as the register_door.
If `name` isn't prefixed, it will be prefixed with "doors:".

Nyancats are independent in the default mod. Nothing else uses them or
their code. Separating it into a separate mod makes it easier for
subgames to remove them. It also makes it easier for a mod to depend
on nyancats, as lots of subgames don't have them.

Default/mapgen.lua: Register biomes, ores and decorations in
singlenode mapgen. These were never disabled anyway because
singlenode was removed from the world creation menu.

* Unused variables
* Unused values (assigned to variables, but overwritten before use)
* Defining already defined variables instead of reassigning to them.

No longer require night to be skipped for resawn position to be saved
Remove constant beds.read_spawns() calls when a player joins as this
is only required once

Instead of using voxelmanip use 'find nodes in area' instead

Remove spaces inside curly brackets
Split lines over 90 columns

- Only remove the TNT craft recipe, tnt:tnt node and the ABM
- Leave tnt:tnt_burning available for explosions in 3rd party mods

- Documentation for sethome.get, sethome.set and sethome.go

Preserve overlapping registrations of large and small clusters
below y = -64 but now extend the small clusters up to y = 0 (the
previous highest iron ore level) in a similar to way to coal

Each ore's rarity is equal to that occuring below y= -1024

Re-order registrations
Add and improve comments
Change sand blob ymax to 0 as sand does not always rise above 0
Remove dirt blobs from sandstone as it is unsuitable for
many sandstone biomes and ugly in stony sandstone desert
Change ymax of first iron region to 0

- Placing liquid inside a protected area no longer returns an empty bucket
- Remove on_place function, tidy up code, return proper itemstack
- Shorten code (changes from HybridDog/patch-35)

- Global functions sethome.set(name, pos) , sethome.get(name) and sethome.go(name)
- Tidy: trim coords to one decimal place and write to table and output table in one go.
- Add error checking
- Add t4im's homepos loader

When waterlilies are placed near river water source make flowing river
water remove waterlilies instead of flowing around them in an ugly way

Changed node sounds for steel door/trapdoor to stone
defaults instead of wood defaults