start of the new refactoring

- close #25 (flatten all the things)
- close #24 (new brewc alias + not called anymore)
- close #22 (cf #24)
- close #10 (using functions instead of bin is the way to fix that)

Now we got
- dotfiles (this project will be renamed after because
dotfiles/dotfiles is stupid)
- preferences (user choices)
- packages (setup + some generic conf) -  this will probably move into
the `setuphs` thing soon
- `setupsh` is the core & will be moved elswhere as a submodule or
something.