Python files are installed into `$DESTDIR/lib/lutris`
Scripts in `/bin` have been edited to search **ALL** module inside this dir
Datas are also searched in `</lib/lutris>/../../share/lutris`, this allow weird DESTDIR like `/tmp/lutris` (tested)
Now Lutris assume that libdir is located in `<bindir>/../lib`
This is minimalist right now and should work for everyone
