WINTERMUTE: Partially fix rotoscale coordinate confusion

This fixes two issues:

* The rendering rectangle was not rotated, causing garbage to be
drawn if the rotated rectangle did not fully cover the unrotated
rectangle, or sprites to be clipped in the opposite case.

* The order of mirror/scale/rotation operations was inconsistent.
This commit does scaling first, followed by rotation. (This is only an
issue because scaling is specified separately in X and Y directions.)
For now only FIXMEs are added for mirroring.