reduce memory allocation, lack of GPU memory totally destroys performance on my GTX 650M on the Macbook retina

add some keys to toggle gui drawing and shadows

src/Bullet3OpenCL/RigidBody/b3Config.h

@@ -32,7 +32,7 @@ struct	b3Config
 		m_maxConvexShapes = m_maxConvexBodies;
 		m_maxBroadphasePairs = 16*m_maxConvexBodies;
 		m_maxContactCapacity = m_maxBroadphasePairs;
-		m_compoundPairCapacity = 16*1524*1024;
+		m_compoundPairCapacity = 1024*1024;
 	}
 };