Fix regression by commit 45f6129a

See http://bugs.musicpd.org/view.php?id=4477

Keep only the last error.  This fixes bogus aborts due to the error
check in decoder_get_virtual_command().

Necessary to preserve type information.  The try/catch sequence didn't
work previously.

Same fix as in commit 1c904000

Tell systemd that MPD is going to notify it when initialization is
done.

This is the final piece for full ID3/APE support in archives.

This code has been moved to LoadFromArchive().

Don't open the ZIP file again and again for each song file.

Load APE/ID3 tags from archives.

This commit adds support for APE/ID3 tags from NFS/SMB files.

See http://bugs.musicpd.org/view.php?id=4270

Fixes deadlock.

release v0.19.13

Fixes disappearing duration of remote songs during playback.

See http://bugs.musicpd.org/view.php?id=4492

The initgroups() manpage says we need to check for _BSD_SOURCE.  The
thing is that glibc deprecated this macro, and doesn't define it
anymore, effectively breaking all MPD supplementary groups.

The real fix is to check for initgroups() availability at configure
time, instead of relying on the deprecated _BSD_SOURCE macro.