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...
eek, this is a half-ass finished rework w.r.t. #966, I'll just remove that here (no such thing as `check_url` yet, so not used anywhere)