Component removal is just about working...

... Stil a bug related to out-of-order revoval of components screwing up the correct cleanup of model view state in the navigator menu host. In detail, if you select an extension point, and create two new subcomponents A and B and remove them in order B, A everything is fine. However, if you remove A and then B (out of order), an internal index maintained by the menu host is broken and the current code path causes a bogus menu item to either be created or orphaned in the children obversable array.