Add the ability to list available games in the repository

[Yrouel]

Now that the list of games is quite long (cool!) it's a bit of an hassle to keep the list of available custom banners up to date so it'll be nice to have the generator spit out the list (generator --list perhaps) of titles (and in the gui maybe even the actual assets)

[lifehackerhansol]

I'll think about it. Shouldn't be hard to implement

Admittedly I haven't really focused on YANBF for a while, since things seem to be working with no big issues.