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.

To replace libcue, the unmaintained and crashy library.

Conflicts:
	NEWS
	configure.ac

Conflicts:
	src/decoder/ffmpeg_decoder_plugin.c
	test/read_tags.c
	test/run_decoder.c

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

Minor optimisation.

Use the tag_item_names table to look up the names of all MPD tags, and
remove the duplicate entries from ffmpeg_tag_maps.

Allow using this function without the ffmpeg_tag_map struct.

Eliminate some duplicate code.

Move the #ifdefs out of _copy_metadata().

No interest in this return value.

Reduce the number of lock/unlock cycles, and make database handling
safer.

This was the cause of the reversed ordering when loading a database
file.

It seems gcc 4.5 does not allow #pragma within function:

 src/input/soup_input_plugin.c:284:9: error: #pragma GCC diagnostic not allowed inside functions

This commit fixes a major regression in directory_lookup_directory(),
which broke the deep lookup of directories.