KiokuDB::GC::Naive - Naive mark and sweep garbage collection

    use KiokuDB::GC::Naive;

    my $gc = KiokuDB::GC::Naive->new(
        backend => $backend,
    );

    $backend->delete( $gc->garbage->members );

This class implements full mark and sweep garbage collection for a backend supporting KiokuDB::Backend::Role::Scan.