Resolve "add carousel theming" + several theming improvments

Closes #52 (closed) Related issue: #35 (closed) Related issue: #27 (closed) Related issue: #14 (closed)

WSOD fix: original work by https://github.com/fieldofcows https://github.com/RetroPie/EmulationStation/pull/88/commits/6872f472772f2d6a2ae5b3971a4434330b5b9ca3

Carousel theming: original work by https://github.com/zigurana https://github.com/RetroPie/EmulationStation/pull/101/commits/ac5e3ad95f34ac52bc925d618f37fe9b1717b42b

Other carousel and theming improvment: original work by https://github.com/jrassa

menu theming inspired by work from https://github.com/jacobfk20

theme subsets, region, helsystem icons and menus by https://gitlab.com/Supernature2k