support for hierarchical module naming schemes

@geimer: this should fix the problem that's blocking you right now

I might need to figure out one more thing w.r.t. the devel module name before this really works for you, I'm looking into that...
this has little to do with singletons, it's simply caching the list of available mns's via an attribute

not really needed though, it won't speed up things a lot at all, so I'll clean it up