Add a new ``mbcollection.remove`` configuration option (default: None)
and a new ``-r`` (``--remove``) flag which removes albums from
collections that are no longer present in the beets database.
The ``-r`` flag takes precedence over the ``remove`` configuration
option.
Add a configuration section that lists all options for each plugin.
List options in alphabetic order.
Mention the default value for each option.
Use same sentences to describe concepts common to different plugins eg 'auto
option, install description