.gz support

[dbenoy]

snes9x supports files like .sfs.gz, but I've noticed they don't come up when selecting a ROM.

I believe this may be a bug. Line 605 in 3dsmain.cpp is: std::vectorstd::string files = file3dsGetFiles("smc,sfc,fig", 1000);

I notice .gz isn't mentioned.

My apologies if gzip support was deliberately omitted.