Updates the Self API to expose more uix.Actor fields:
* Doodad()
* GetBoundingRect()
* HasGravity()
* IsFrozen()
* IsMobile()
* LayerCount()
* ListItems()
* SetGrounded()
* SetWet()
* Velocity() - note: it was Self.GetVelocity() before.
Self.GetVelocity is deprecated and made an alias to Velocity.
