Merge: Cleanup and synchronize options in manpages

A tedious work to detect and fix undocumented options in the manpages of tools.
This also synchronizse the description of `--help` and the text in manpages (when there is a diversion, the best one if often selected).

Cherry on the cake: a new script `check_manpage` can automatically check that new options of tools are documented in the man. Close #1772

Pull-Request: #1778
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>

diff --cc src/loader.nit
Simple merge