Instead of having a physics node named Static that can be either Static
or Kinematic, AnimatableBody is added again as a separate node:
-Inherited from StaticBody to make its usage clearer
-Still separated from CharacterBody to make its usage more focused
Properly implemented constant velocity for kinematic bodies in godot
physics servers (induced velocity without actually moving).
Also updated description for the different physics nodes to make their
usage clearer.
Does the same thing as simulate motion from RigidBody in Kinematic mode,
and CharacterBody (previously KinematicBody).
Added support for constant linear/angular velocity with kinematic_motion
in StaticBody, which moves the body in physics.
Updated documentation for StaticBody and CharacterBody to describe their
functionalities more accurately.
