fixed some outstanding issues with Bullet soft bodies:

1) re-allocate a pool allocator, if one of the soft body collision algorithms is larger than max pool element size
2) manage child shapes properly, and call RemoveReferences on the m_sparsesdf

src/BulletSoftBody/btSoftBody.h

@@ -609,6 +609,11 @@ public:
 
 	btAlignedObjectArray<int>	m_userIndexMapping;
 
+	btSoftBodyWorldInfo*	getWorldInfo()
+	{
+		return m_worldInfo;
+	}
+
 	virtual void	setCollisionShape(btCollisionShape* collisionShape)
 	{
 		//don't do anything, due to the internal shape hack: todo: fix this