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...
the longer you delay it, the bigger the pain gets, to the point where you won't touch it anymore and you might just as well start from scratch. 
i don't understand why the `_file` functions are a can of worms. (and don't be afraid to make new modules, you don't have to put everything in `filetools`, nobody will die if you make a new module with a less generic/meaningless name)