Ability to scrap all roms in zip/gzip Romset archive

[arcane47]

The current Hasher only returns the first known valid decoder in a romset archive. This may be a modded ROM with no valid hash, while the remaining entries in the archive represent valid scrapable hashes.

[sselph]

I don't think it is possible to scrape every rom in a zip (gzip isn't an archive so can only contain 1 file) since the gamelist only allows one entry but maybe I could parse every file until I find a matching hash. I'll look in to it but my next priorities are getting this code integrated in to EmulationStation.