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...
it might make sense to have a `full_mod_name` attribute in the easyconfig instance (so this would become 
```
self.mod_name = self.cfg.full_mod_name
```
there is a one-to-one mapping between easyconfig instances and the full_module_name, right?