* Cleanup the "mbsubmit" plugin to remove a choice ("print tracks and skip")
and make the logic depend on the strength of the Recommendation.
* Add configuration options for the Recommendation threshold that triggers
the addition of the "Print tracks" choice and for the formatting string to
be used for printing the items.
* Include link to the official-ish MusicBrainz format page on the docstring.
* Fixes for documentation of the prompt event (missing reserved letter, typos).
* Update sample mbsubmit plugin to conform to the new PromptChoice structure.
* Update mbsubmit plugin in order to use PromptChoice instead of the previous
ExtraChoice.
* Remove comments as they are now present on the pull request and documentation.
* Add example "mbsubmit" plugin, which allows the user to print the tracklist
of an unmatched album during the import process in a format understood by
MusicBrainz track parser.
* The plugin listens for the before_choose_candidate event and appends the
track printing options depending on the task status (candidates and
recommendation).
