Minor housekeeping changes to entities
Added PathPlatformEntity.OnAlreadyThere. It and OnMovementEnd now give current position as parameter
Added LogicEntity (ent_logic), which encompasses logic_auto, logic_relay and logic_compare
Citizen/animgraph: center poses are now applied additively based on move_groundspeed + more comments
This change fixes footstep distances being increasingly inaccurate as movement speed got closer to 0, and it also helps make the transition from moving to idle look much smoother, because the application of the center pose can be slightly delayed through damping.