Simplify and rearrange SkinSelectionHandler
Simplify and rearrange SkinSelectionHandler

The file has been restructured and reworded such that there are as few
differences as possible from b36b40cb3430e6bd511390f82c39ba23195dc8cb.

UselessToucan/osu,UselessToucan/osu,peppy/osu,NeoAdonis/osu,UselessToucan/osu,smoogipoo/osu,peppy/osu-new,NeoAdonis/osu,NeoAdonis/osu,ppy/osu,smoogipooo/osu,ppy/osu,peppy/osu,peppy/osu,smoogipoo/osu,ppy/osu,smoogipoo/osu