Change genre abbreviations to full names.

[madmaxoft]

The abbreviations should only stay in the default template filters' names; everywhere else should use full genre names, to avoid confusion.

[madmaxoft]

@kalich5 Thoughts on this? Good or bad?

[madmaxoft]

Migration:

• Existing song metadata can be auto-upgraded using a DB version upgrade script
• Existing template filters can be auto-upgraded using a DB version upgrade script
• When importing template filters from XML, a special "upgrade" can be added

Points to consider:

• Abbreviations can be tricky (RU vs RB, SA vs SB vs SL)
• Abbreviations take less UI space (song property columns)
• Abbreviations are fixed; full name can be left freely editable for new genres.

[madmaxoft]

Option: Keep the genres stored as abbreviations, but translate them in UI to full names - in the song property editor and template filter editor. This way we can translate the full names, yet keep the filters simple and language-independent.
Keep the genre field freely editable, an unknown value will not be translated; if a new known genre is added later on, it can translate these values in DB upgrade scripts.