Replaced retroarchBare with retroarchBareMaster, also added a few new libretro cores

retroarchBare was too old for any practical use at this point, so it was removed in favor
of fetching releases from git. RetroArch often recommends checkout out the latest git master
if you are on a desktop platform, so we are conforming with their recommendation. I plan on
bumping the git of retroarch and each core every month, and I plan on adding more libretro
cores in the future.

The libretro cores that were added are nestopia, quicknes, snes9x, and vba-m

planned next are : bsnes-accuracy, bsnes-balanced, bsnes-performance, a few libretro mame ports

Closes #4448