Added -root flag support

Not sure if useful, but I had nothing better to do...feel free to tell me it's BS:

I added a command line flag `-root <rootdir>` which can be specified when invoking
the maud executable to change the server root.
Also, the default server root is now set to the dirname of the maud executable instead
of the directory which you launch the server from, so a `../maud` will set the root dir to `..`, not `.`
(in other words, you can launch the server from wherever you want...yeah, no big advantage).

(uso l'inglese per abitudine, se preferisci l'italiano dimmelo)
:+1: