supports ducking
floor collision bug fixes
adds sliding underneath ceilings while escaping ducking
Merge branch 'master' into duck

Conflicts:
	src/nodes/floorspace.lua
	src/player.lua
reverted floorspace change
locks the player into his original ducking direction
fixed jumpkill bug

Conflicts:
	src/nodes/enemy.lua
Merge branch 'master' into duck_merge

Conflicts:
	src/nodes/block.lua
	src/nodes/enemy.lua
	src/nodes/floor.lua
	src/nodes/platform.lua
	src/nodes/wall.lua
ignores platforn collisions with player's head
removed unnecessary files
improved duck sliding
fixes top bb block jumping
simplifies ducking code
Merge branch 'master' into duck

Conflicts:
	src/nodes/enemy.lua
Merge pull request #680 from NimbusBP1729/duck

supports ducking (treadmilling fixed!)