Minor code cleanup, renamed a variable and function.
The position and rotation of an IPO animated physical object from a library
must be transformed by the transform of its (graphical) parent (only library
nodes have a graphical parents) to be correct.
When the physics are updated from the graphics, subtract the
graphical offset again to make sure physics and graphics are in sync.
Merge branch 'master' of github.com:supertuxkart/stk-code