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...
problem is that these functions use `det_toolchain_element_details`, which *has* to live in the `easyconfig` namespace because if requires `robot_find_easyconfig`; there's no way around this without including cyclic deps (`easyconfig` requires `toolchain`, so `toolchain` can't require `easyconfig`)