Zyps

Behavior switching improved.
GUI actions streamlined.

Full changes:

SpeedLimit added.
bin/zyps action magnitudes tweaked.
PushAction, PullAction added.
ProximityCondition added to all behaviors in bin/zyps.
bin/zyps controls revised.
Behavior.perform now takes an entire Environment, not a specific GameObject.
Added test_object_removal.
DestroyAction now passes all tests.
Now uses Enviroment#interact instead of having actions act directly.
rdocs updated.
Action#start, Action#end added.
Behavior modified to target on only one object until a condition is false.
Removed stray green creature from site title image.