Improvements to ASF tags:

* Distingiush between WM/OriginalReleaseTime and WM/OriginalReleaseYear
* Save encodersettings to WM/EncodingSettings
* Save website to WM/AuthorURL
* Support WM/PartOfSet possibly containing totaldiscs
Fix the working directory for shortcuts created by the Windows installer

In NSIS the working directory for shortcuts is controlled by the SetOutPath variable, see http://nsis.sourceforge.net/Docs/Chapter4.html#createshortcut . In our case this caused the working directory to be set to the "locale" directory.

Fixes [PICARD-649](http://tickets.musicbrainz.org/browse/PICARD-649)
Added tests for Musepack v7 and v8
Merge branch 'mpc-tests' of github.com:phw/picard
Merge branch 'fix-win-installer-working-directory' of github.com:phw/picard
Merge branch 'improved-wma-tags' of github.com:phw/picard