Add %_live%, %_cover% etc. for work relationships.
Add NEWS
Switch variable names and add ~workrelationship

which mimics the work relationship statement on the MB web site e.g.
`{live} {medley:medley including a} {partial} {instrumental} {cover}
recording of`
Handle i18n differently ...

... so that work relationship text can be translated as a phrase and not
as individual words.
Fix metadatabox sort order

Sort by displayed value not internal value.
Merge pull request #297 from Sophist-UK/sophist_fix_metadata_display_sort_order

Fix metadatabox sort order
Remove ~workrelationship stuff.
Merge pull request #285 from Sophist-UK/sophist_add_work_relationship_variables

Add %_performance_live%, %_performance_cover% etc. for work relationships.
Add sorted versions of Performer etc.

so user can override ordinary performer with sorted version if they want
to.

Plugin to do this to be added in a second commit.
Add plugin
Add NEWS
Make plugin non-class
Switch back to standard metadata access.