Add aabbMin/aabbMax to broadphase proxy, and improve rayTest performance.

Todo: use broadphase acceleration structure (btDbvtBroadphase etc) for ray test

src/BulletCollision/CollisionDispatch/btCollisionWorld.h

@@ -107,6 +107,11 @@ public:
 		m_broadphasePairCache = pairCache;
 	}
 
+	const btBroadphaseInterface*	getBroadphase() const
+	{
+		return m_broadphasePairCache;
+	}
+
 	btBroadphaseInterface*	getBroadphase()
 	{
 		return m_broadphasePairCache;