On some platforms, g_free() must be used for memory allocated by
GLib.  This patch intends to correct a lot of occurrences, but is
probably not complete.

We have two mod plugins now: modplug and mod.  Rename the latter to a
more useful name.

EOF is checked by input_stream_read() (decoder_read() here).  Don't do
it twice.  The check was wrong anyway, it was reversed.

When input_stream_read() returns 0, and input_stream_eof() returns
false, an I/O error has occured.  Skip this song.

Don't enlarge the GByteArray when the size limit may overflow in this
operation; check the size limit first.

The local variable "total_len" is superfluous because GByteArray
always knows its size.

The input_stream API sets size to -1 when the size of the resource is
not known.  The modplug decoder checked for size==0, which would be an
empty file.

Don't include utils.h and log.h, they are relics from the past.

Make sure that log messages are decorated correctly.

Don't write CPP if you can write C.

You are allowed to call decoder_read() with decoder==NULL.  It is a
convenience function provided by the decoder API.  Don't manually fall
back to input_stream_read().

alternative settings must be set before the file
is loaded, otherwise they won't be respected.

The plugin queries build-time configuration variables, and should
include config.h.

Some plugins used the APE or ID3 tag loader as a fallback when their
own methods of loading tags did not work.  Move this code out of all
decoder plugins, into song_file_update().

When libvorbis knows that a song is seekable, it seeks around like
crazy in the file before starting to decode it.  This is very
expensive on remote HTTP resources, and delays MPD for 10 or 20
seconds.

This patch disables seeking on remote songs, because the advantages of
quickly playing a song seem to weigh more than the theoretical ability
of seeking for most MPD users.  If users feel this feature is needed,
we will make a configuration option for that.

This patch allows mpd to recognise the albumartist tag in the way
foobar2000 and others write it to files.

Splitted flac_copy_vorbis_comment() into flac_copy_comment() and
flac_copy_comment().

Simplify flac_copy_vorbis_comment() by moving the comment
identification code out.

Free the tag object when it turns out to be empty.  This simplifies
several functions and APIs.

Use tag_is_empty() instead.

Renamed types, functions, variables.

This patch allows mpd to recognise the albumartist tag in the way foobar2000
and others write it to files.

Don't depend on the daemon's locale settings.  Comment names are
ASCII.

vorbis_parse_comment() should be a function which converts one comment
to a tag item.  It should do everything required to do the conversion,
including looping over all possible tag types.

Eliminate some duplicate code.

Always allocate a new tag object before parsing the vorbis comments;
free it when it turns out to be empty.  This simplifies the code a
bit.

Renamed functions and variables.

Make ogg_parseCommentAddToTag() return bool instead of unsigned int.

"#ifdef G_BYTE_ORDER == G_BIG_ENDIAN" cannot work, of course.

Removed all allocation functions, xwrite(), xread(), ARRAY_SIZE().
Those have been superseded by GLib.

Use G_GNUC_UNUSED instead of mpd_unused (which has already been
removed).

Use GLib's G_GNUC_UNUSED instead of gcc.h's mpd_unused.