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...
moving it outside of `easyconfig` isn't possible, for the same reason as stuff can't be moved into `toolchain`: avoiding cyclic deps (there's no way around it, trust me)