Adding traceback to exception report.
Bug fix: format of this dictionary changed.
Formatting
Workaround: apparently, MusicBrainz is not happy with spaces in the catalog number when searching.
Adding command to find releases by release group ID.
This should no longer be necessary; might break other things for now.
Revising purchase entry code.
Combining date-prompting code into a function. Revising checkin and checkout shell commands.
Fixing formatting of prompt. Prompting user to add the release associated with a disc.
Adding a text mode progress bar to mbcat.dialogs. Replacing the sync collection and catalog rebuild commands with progress bar, thread creation and thread waiting.