Make sure the queue "owns" all song objects, so nobody else can free
them.

Eliminates explicit global initialisation.

GLib 2.16 was released more than 4 years ago.  Let's remove some cruft
from the glib_compat.h header, and avoid new cruft to it.

This plugin is horrible code, I mean it.  Last year, I tried hard to
fix it, but I figured would take less time to do a full rewrite.
Given that I don't even have any device that supports RAOP, I can't do
that properly.  After 16 months, nobody volunteered for fixing it.
Hereby, I delete it, because having no RAOP plugin is better than
having this mess.  Sorry.

Add the encoder_plugin method end().  This is important for the
recorder plugin.

Delete the now-unused pcm_byteswap library, and optimize the
pcm_export_state object.

Eliminate support for reverse endian samples from the MPD core.  This
moves a lot of complexity to the plugins that really need it (only
ALSA and CDIO currently).

Some compilers are very picky, but we really aren't interested in the
return value.

Some compilers are very picky, but we really aren't interested in the
return value.

Make sure we get a UTF-8 encoded string.

Parses CUE data from the "CUESHEET" tag.  Needs further integration in
the update thread.

The new method pair() receives an arbitrary name/value pair.  Support
for this is being added to a few decoder plugins.

Pass a callback table to scan_file() and scan_stream(), instead of
returning a tag object.

Didn't compile on GLib < 2.16.

This is easier and more efficient to loop on, because only two
variables get modified (src and dest).

The other audio_format attributes are not used.

In a C file, that is too late, because _mingw.h defaults to 0x0502,
and ours would be illegal redefintion.

Needed for the I/O thread.