#6 Add convex decomposition for TriMesh objects

[Manfred Kröhnert]

If multibodies work (Ticket #5) they can be used to represent an object after it has been decomposed.
This is done in openRAVE for example.

Some decomposition algorithms:

• http://codesuppository.blogspot.com/2006/08/approximate-convexdecomposition.html
• http://www.cgal.org/Manual/3.5/doc_html/cgal_manual/Convex_decomposition_3/Chapter_main.html