* bugfix for BGE python api - SetParent actuator getObject would segfault if the object was not set.
* Added utility function ConvertPythonToGameObject() that can take a GameObject, string or None and set the game object from this since it was being done in a number of places.
* allow setObject(None), since no object is valid for actuators, Python should be able to set this.
* added optional argument for getObject() so it returns the KX_GameObject rather then its name, would prefer this be default but it could break existing games.
This patch consists in new KX_GameObject::SetParent() and KX_GameObject::RemoveParent() functions to create and destroy parent relation during game. These functions are accessible through python and through a new actuator KX_ParentActuator. Function documentation in PyDoc.
The object keeps its orientation, position and scale when it is parented but will further rotate, move and scale with its parent from that point on. When the parent relation is broken, the object keeps the orientation, position and scale it had at that time.
The function has no effect if any of the X/Y/Z scale of the object or its new parent are below Epsilon.
