Added a gCompoundChildShapePairCallback to filter (enable/disable) child shape collisions for a btCompoundShape.

Thanks to Rich McDaniel for the patch.
See MyCompoundChildShapeCallback in Demos/ConvexDecompositionDemo/ConvexDecompositionDemo.cpp for usage.

Demos/ConvexDecompositionDemo/ConvexDecompositionDemo.h

@@ -75,6 +75,8 @@ public:
 
 	virtual void displayCallback();
 
+	virtual void keyboardCallback(unsigned char key, int x, int y);
+
 	static DemoApplication* Create()
 	{
 		ConvexDecompositionDemo* demo = new ConvexDecompositionDemo();