a convex hull collision shape. Disabled by default, set bevel-factor in stk-config (e.g. to 0.3 0.3 0.3). git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@10466 178a84e3-b1eb-0310-8ba1-8eac791a3b58