Fix for T41536: 2.71 getActionFrame no longer returns frames accurately

Fix for T41536: 2.71 getActionFrame no longer returns frames accurately

We now keep actions around when they are finished playing so scripts can
still get access to information such as the current frame. Playing a new
action in the same layer still overwrites the previous action as before this
commit. Using an explicit KX_GameObject.stopAction() will free the memory. The
action is also freed when the KX_GameObject is freed as before.