Partially reverted previous commit

ContactListener is a member of PhysicHandler now.
This is the right design decision and avoids a bug with duetto
Merge branch 'master' into cutting
Workaround for duetto std::set bug
Implement scoring
max speed parametric to level
Changed game background for cutting
Implemented gameover falling
Improve test: added testconvexer & fix wrong comment about ipothesis
convexer: first point of second pol in common(fix)

This behaviour is expected by graphichandler simple tessellator