- allow reading of only select fields in systemd.journal._reader.Reader
- export sd_journal_test_cursor in systemd.journal._reader.Reader
- export sd_journal_get_usage in systemd.journal._reader.Reader
+ - add systemd.journal._reader._Reader.closed attribute (it can
+ be just "return self->j != NULL")
- figure out a simple way to wait for journal events in a way that
works with ^C