games skin update

Retroarch is now available on Steam!

It is still early days for Retroarch's integration in steam (regarding playlists and other assets like thumbnails).

bug fixes

1. Steam has changed the structure of their internal library.vdf file. This resulted in duplicate game/app entries because I previously had to manually add the path to the installed steam executable as a library.
2. I had to compensate for spaces in the path to Retroarch's steam install.

other

converted tabs to spaces (mostly in Lua scripts only)

Full Changelog: 0.8.0...0.8.1