Floor refactor, try #1
Floor revamp: fixed runtimes and a couple mistakes
Merge remote-tracking branch 'upstream/master' into attackoftheturfs

Conflicts:
	code/game/mecha/equipment/tools/medical_tools.dm
Floor refactor: fixes floor tile icon_state switching, removes uneeded spawns, cleans up old cruft and redundant code

Fixes #1839

Fixes #2797
Readds the built-in floor tiles for a singulo purpose.
Merge remote-tracking branch 'upstream/master' into attackoftheturfs
Fixes botcall conflicts, removes even more cruft and unused code
Merge pull request #5357 from tkdrg/attackoftheturfs

Floor refactor