Rotate, RotateWorld script instructions and local rotations
For the Rotate instruction, we need to support local rotations, which are applied relative to the CellRef's rotation. This is probably a prerequisite for #74 (closed).
(RM-658 from redmine: created on 2013-03-22 by scrawl ., , closed on 2013-04-25 by Michał Bień)