assign proper index when removing a child shape from btCompoundShape

Thanks to sparkprime for the report and fix in Issue 354
See http://code.google.com/p/bullet/issues/detail?id=354
Fix a few warnings

src/BulletCollision/CollisionDispatch/btCompoundCollisionAlgorithm.cpp

@@ -114,7 +114,9 @@ public:
 
 	void	ProcessChildShape(btCollisionShape* childShape,int index)
 	{
-		
+		btAssert(index>=0);
+		btAssert(index<compoundShape->getNumChildShapes());
+
 		btCompoundShape* compoundShape = static_cast<btCompoundShape*>(m_compoundColObj->getCollisionShape());
 
 

src/BulletCollision/CollisionShapes/btCompoundShape.cpp

@@ -110,6 +110,8 @@ void btCompoundShape::removeChildShapeByIndex(int childShapeIndex)
 		m_dynamicAabbTree->remove(m_children[childShapeIndex].m_node);
 	}
 	m_children.swap(childShapeIndex,m_children.size()-1);
+    if (m_dynamicAabbTree) 
+		m_children[childShapeIndex].m_node->dataAsInt = childShapeIndex;
 	m_children.pop_back();
 
 }