COMMIT THAT BREAKS EVERYTHING! This is the new API

Modules now reside in the `modules` subfolder. Also, each module
directoy has a slightly different file structure now:

* `mod_<modulename>.h` for each module is split into `register.h` and
  `prototype.h` (so no bloody #ifndef magic)
* `mod_<modulename>.c` is renamed to `module.c` (for any module)

This makes everything more uniform, and the API documentation simpler
(muahaha). By the way, that one has been updated, too (but NOT the user
documentation, needs to be done ASAP).

In karuibar itself, fix the bug that assigns the dummy module a `name`,
but not a `basename`.