Improved URDF support for btMultiBody and separate graphics/collision/inertial frames and shapes

Fix WinXP GetTickCount64 with a typedef
Expose debug drawing mode/flags in UI (hot keys A,D,L,W for now, buttons later)
GLInstancingRenderer: tweak near/far planes to allow closer approach of camera
btDiscreteDynamicsWorld: enable debug drawing for btGeneric6DofSpring2Constraint
btMultiBodyDynamicsWorld: enable basic debug drawing for btMultiBody
btMultibody: allow center-of-mass shift for prismatic and fixed constraint

src/BulletDynamics/Featherstone/btMultiBody.h

@@ -61,7 +61,8 @@ public:
 						   const btVector3 &inertia,
 						   int parent,
 						   const btQuaternion &rotParentToThis,
-						   const btVector3 &parentComToThisComOffset,
+						   const btVector3 &parentComToThisPivotOffset,
+                           const btVector3 &thisPivotToThisComOffset,
 						   bool disableParentCollision);