* clutter/clutter-behaviour-rotate.c:
* clutter/clutter-behaviour-rotate.h:
Split 'center' prop into 3 seperate props for each axis.
Use clutter_behaviour_actors_foreach() rather than
clutter_behaviour_get_actors() to avoid copying list.
Call fixed point rotation funcs internally.
* clutter/clutter-effect.c:
* clutter/clutter-effect.h:
Add new simple rotation based effect funcs.
Add initial implementation of a rotate behaviour; this behaviour rotates
actors along a chosen axis, with a chosen direction, between two angles.
Missing: API documentation and the implementation for the angle boundaries
setters (double and fixed API).
