Remove the requirement for game abbreviations to be unique. Whilst cleaning the game section, I found a lot of conflicting abbreviations. For example: Company of Heroes and City of Heroes. I'd rather have them both be CoH, since the abbreviation isn't really used for anything, and there already are games with the same abbreviation (I assume that happened from either the past when it was allowed or after the merge of fps, rts and rpgbanana) which aren't causing any problems. Naturally, gamedir names will still be unique.