APlayer agressively steals mime types

[pulkomandy]

When first starting APlayer, it should only register mimetypes that don't already have a preferred app. So MediaPlayer should still be usedfor mp3/ogg/wav, unless the user explicitly changes that in APlayer preferences or in Filetype.

Moreover, seems we are not agreeing on the MIME type: audio/ogg vs audio/x-vorbis, that kind of thing. And mistakenly tagging mp3s as audio/x-vorbis.