Add higan and visualboyadvance?

[icefoxen]

Part of it is just me being bad at figuring out how to use it, but RetroArch is a giant pain and only sometimes work. Could we add shortcuts to Higan and VisualBoyAdvance to the "Retro games" menu, or are there problems with those particular emulators? I've only tried to get them to work a little bit and it does not seem straightforward, but shouldn't be that hard, hopefully. Would you accept a PR that does this?

[cuu]

have you compiled these emulators successfully on gameshell now?

[icefoxen]

There's binaries for both in the Debian repositories. VBA appears to run but doesn't display properly, Higan starts but then crashes with an X11 error. I've built and run other programs on Gameshell, it seems to just use X11 and OpenGL for display, so it should be possible. I'll keep working on it.