Remove GLib dependency from some headers.

functions to new dsdlib. Update user doc.

g_file_test is redefined to be g_file_test_utf8 and thus can't handle
non-ASCII characters. This fix adds simple wrapper (taken from glib)
that fixes encoding and calls g_file_test_utf8. All required inclusions
of glib_compat.h are added as well.

"Frame skipped" might cause the impression that the decoding of a whole
song failed.

Version 4 of my patch to add DSF support to the DSDIFF
decoder plugin.

This time I have taken a different approach and created a new
read_metadata function specific for reading DSF files. This saves an
indent (and for me a lot of indent nightmares) and also useful for
splitting the DSF and DFF decoders later on.

There are still a few lines which exceed the 80 character width limit by
a few chars. I was not able to stay within the limit and create (for me)
readable code.

Jurgen

DSD-over-USB should not be a MPD core format, because it is not a
"natural" format; it is just a temnporary over-the-wire format.  This
format has been implemented in pcm_export, and does not need to be
supported by pcm_convert.

For simplicity, the MPD core should not have to deal with packing.  It
is rarely used, and those plugins that need it should use the
pcm_export library instead.

Don't use audio_format.reverse_endian.

This format is unused since the DSDIFF decoder plugin now reverses the
bit order.

Allow to remove this complexity from the MPD core.

This might break older versions, I didn't test.

Move the responsibility for the conversion to the PCM library.  This
will allow passing the verbatim DSD samples to an output plugin.

Basic support for Direct Stream Digital.  No conversion yet, and no
decoder/output plugin support.

This might break older versions, I didn't test.

This was disabled when compiled with a new ffmpeg version.  Older
ffmpeg versions used it explicitly, while newer ones may pass it
through from the codec.

Prepare for big CUESHEET tags.

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

Remove clutter from wavpack_scan_file(), and use a (large) fixed
buffer for the tag item.

Fixes build regression.

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

When gme_track_info() returns with success, then the gme_info_t
pointer must be set.

All supported ffmpeg/libav versions have this.

The only other libFLAC call (seek) does not produce fatal errors.

Call it in the function that also invokved
FLAC__stream_decoder_init_*().

https://www.xkcd.com/292/

The struct is smaller because it is sparse.  Its traversal is also
more efficient.

Implements support for libavcodec 0.9, which removes the compatibility
macros SAMPLE_FMT_*

Minor optimisation.