Because the fire nodes are not removed 100% when there are
no more burnable nodes nearby, they can potentially stay around
for very, very long times, leading to ABM trains every 5 seconds
for no good reason (only 1 in 16 will be removed every interval).

A much better method to remove fire nodes is to remove them by
timer, and give removal a 100% chance if no flammable nodes are
adjacent. This makes fire cleanup a lot faster and more natural,
and will reduce the amount of ABM hits making fire overall more
responsive.

We also remove the 1 in 4 chance and fold the removal of flammable
nodes into the ABM chance.

There's some low hanging fruit cleanups in here as well.

Flammable nodes burn away quicker

No need to find_node_near twice with the same params.

Spread ABM intervals evenly across 1 to 16 seconds
16s ensures no nodes are missed when player walks past
Adjust chance values to compensate, for identical action rates
Combine lavacooling ABMs into one, return to chance = 1
Grass growth: add 'neighbors = "air"' to avoid
processing the thousands of underground dirt nodes
Grass death: Reduce action rate to that of grass growth
Fire: Use chance = 1 for flame extinguishing
and flame removal when mod is disabled

To avoid processing spikes where catch-up is non-essential
Disable in: Lavacooling, grass growing, grass removal
and all fire mod ABMs

Update 'disable fire' documentation in conf.example

Rename in game.conf and documentation
Update game_api.txt documentation for bucket API and tree functions
Fix tab, space and comment formatting in game_api.txt
Rename in mod READMEs

Add extinguish sounds (from default mod lavacooling)
'disable fire' setting extinguishes fire quickly using a dedicated ABM
'disable fire' also disables all other ABMs
Simplify flammable node removal ABM
Speed up node ignition, it was too slow
Add 'sunlight propagates = true' and 'paramtype = "light" to flame
Balance fire sounds' gain

Increase chance value of ABMs
Disable ignition from a distance
Only detect neighbouring extinguishing nodes
Fix code style issues and add comments

Implemented nodes:
- Steel Door: Ignores explosion
- Locked Chest: Ignores explosion
- Fire: Ignores explosion
- TNT: Starts burning
- Burning TNT: Explodes immediately
- Gunpowder: Starts burning
- Burning Gunpowder: Ignores explosion

This reverts commit dcce6e97.