Refactor avatar movement code

plMovementStrategy classes have been reworked and completely replace all plAvatarControllers.
While based on the old implementation, plPhysicalControllerCore has essentially been rewritten.
Remnants of long gone physical "actions" have been removed.

4 files removed -
plAVCallbackAction.h & plAVCallbackAction.cpp
plAntiGravAction.h & plAntiGravAction.cpp

This revision will not compile, requires new plPXPhysicalControllerCore implementation.

Sources/Plasma/FeatureLib/pfPython/pySceneObject.cpp

@@ -554,7 +554,7 @@ bool pySceneObject::IsAvatar()
     return false;
 }
 
-#include "plAvatar/plAvCallbackAction.h"
+#include "plAvatar/plPhysicalControllerCore.h"
 
 PyObject* pySceneObject::GetAvatarVelocity()
 {