Convert if/else/else/... to a loop.

Allow code sharing.

I took this tag name from a MusePack sample file I got from a user.
It is not documented in the APE specification:

 http://wiki.hydrogenaudio.org/index.php?title=APE_key

People seem to be using undocumented extensions to the specification
anyway, and the best we can do is attempt to support them.

Make "enum tag_type" the array index, and convert apeItems to a sparse
array.

Improve code readability.

Don't initialize those arrays each time tag_ape_load() is called.

Without libid3tag, we were trying to skip the ID3 frame (since
0.15.2).  Its length however was not calculated at all, we were just
dropping everything from the current input buffer.  This lead to the
first few seconds of the file being skipped.  This patch attempts to
calculate the ID3v2 frame size with the formula from:

 http://www.id3.org/id3v2.4.0-structure 3.1 and 6.2

"When playing musepack files with mpd v0.15.8, rg seems to have no effect.

Using sample file below, mpd says 'computing ReplayGain album scale with gain 122.879997, peak 0.549150'.

One thing though, if I build mpd against old libmpcdec-1.2.6, rg works
as expected: 'computing ReplayGain album scale with gain 16.820000,
peak 0.099765'"

Previously, tags of the new song being cross-faded in were sent
immediately.  That can cause wrong information being displayed,
because the "previous" song might send its tag at the end again,
overriding the "next" song's tag.  This patch saves & merges the tag
of the next song, and sends it when cross-fading is finished, and the
next song really starts.

Like tag_merge(), but can deal with NULL parameters, and frees both
tag objects.

"There is a bug in fixed-point musepack (musepack_src_r435) playback.
In floating-point audio is OK but in fixed audio is distorted.  I have
made a patch for this"

With single+repeat enabled, it is expected that MPD repeats the
current song over andd over.  With random mode also enabled, this
didn't work, because the song order was shuffled internally.  This
patch adds a special check for this case.

Removed the decoder_command_finished() call at the end of
mp3_decode().  This is invalid, because decoder_command_finished() has
already been called in mp3_read().

Taken from the ffmpeg sources.

Needed for the fluidsynth decoder plugin.

To allow libavformat to detect the format of the input file, append
the suffix of the input file to the URL of the virtual stream.  This
specifically enables the "shorten" codec, which is supported by
libavformat/raw.c, detected only by the suffix.

Allow declaration after statement.

Check consume mode in queue_next_order(), because the current song
would be deleted as soon as it's finished; it cannot be played again.

The patch "input/file: don't fall back to parent directory" introduced
a regression: when trying to play a CUE track, decoder_run_song()
tries to open the file as a stream first, but this fails, because the
path is virtual.

This patch fixes decoder_run_song() (instead of reverting the previous
patch) to accept input_stream_open() failures if the song is a local
file.  It passes the responsibility to handle non-existing files to
the decoder's file_decode() method.

This fixes a regression in the patch "return multiple tag values per
song": even when the song has values for the specified tag type, the
empty string gets added to the set, because the "return" was removed.
This patch adds a flag which remembers whether at least one value was
found.

This has been reimplemented in the "rewind" input plugin.

This replaces the rewinding buffer code from the CURL input plugin.
It is more generic, and allows rewinding even when the server sends
Icy-Metadata (which would have been too difficult to implement within
the CURL plugin).

This is a rather complex patch for the stable branch (v0.15.x), but it
fixes a serious problem: the "vorbis" decoder plugin was unable to
play streams with Icy-Metadata, because it couldn't rewind the stream
after detecting the codec (Vorbis vs. FLAC).

Support deprecated MIME types such as "audio/x-ogg".  Support new
types such as "audio/flac".

When collecting tag values for the result set, add all of a song's tag
values of the searched type.  This affects the "list" command.
Previously, "list" only considered the first tag value of a song.

Don't clear the music pipe when seeking has failed - check the
"seeking" flag instead of "command==SEEK".  Clear the "seeking" flag
in decoder_seek_error().

First multiply the floating point return value of
decoder_seek_where(), then cast to integer.

Free the "context" pointer in the method archive_plugin.close().