metadata support
================
there's two main alternatives:
 - a dialog with prev/next and group edit and set/reset button
 - a widget with prev/next and group edit and automatic saving of changes
other things to consider:
 - use regular expressions to guess tags from filenames as fallback mechanism
 - if a permanent widget is used, "disconnect" it when hidden
 - allow editing of multiple files simultaneously
 - allow moving fordward/backwards on the items list
 - disable/enable the metadata widget state according to job state (encoding/enqueued/idle)

Other things
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 - separate naming scheme option from encoding profiles (add a new type of profiles)
 - think of a better way to display and set naming scheme and encoding profiles
 - add decoders priority configuration (mp3PRO files must be decoded by wadump, but it's too slow for general use)
 - check support for WavPack and OptimFrom hybrid compression schemes (WavPack Hybrid and OptimFROG DualStream)
 - check multiple jobs and realtime progress indication bug

 - add support for streams ripping through streamreaper
 - add support for cd ripping through cdparanoia
 - add support for xmms plugins
