(Blocked on #110) xbescanner: Adds mechanism to load save game icons.

[abaire]

I thought it might be interesting to show the save game icon for either all of the XBEs or the actively selected one. This puts in the infrastructure to make this possible (I'll send a draft PR with a really ugly proof-of-concept shortly).

[dracc]

I really like the idea of this, but I fear it might slow down hw renderer progress significantly. Might be a while before I merge this.

[abaire]

No problem, given that the framerate is already quite low on hardware I think it's entirely reasonable to let this sit until accelerated rendering is available. Hopefully we can also render the DXT1 textures without having to decompress them as well.

[abaire]

Putting in draft until #110 is resolved