This filter takes a set of primary keys for rows that should be visible
during filtering. Passing None as a value means that all rows are shown.
It also has functions for adding or removing individual rows from the
filter.
Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>
This will be shared between settings, playlists, and tracks so we have a
common interface for working with database rows.
Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>
