Remove co-planar faces from convex hull, using 2d Graham scan

Improve SAT performance, by skipping back-facing features
Add assert in array class (probably fires in places)

src/BulletCollision/CollisionDispatch/btSimulationIslandManager.cpp

@@ -47,6 +47,8 @@ void btSimulationIslandManager::findUnions(btDispatcher* /* dispatcher */,btColl
 	{
 		btOverlappingPairCache* pairCachePtr = colWorld->getPairCache();
 		const int numOverlappingPairs = pairCachePtr->getNumOverlappingPairs();
+		if (numOverlappingPairs)
+		{
 		btBroadphasePair* pairPtr = pairCachePtr->getOverlappingPairArrayPtr();
 		
 		for (int i=0;i<numOverlappingPairs;i++)
@@ -63,6 +65,7 @@ void btSimulationIslandManager::findUnions(btDispatcher* /* dispatcher */,btColl
 					(colObj1)->getIslandTag());
 			}
 		}
+		}
 	}
 }