Closes #277

These are used by DSD-streaming servers.  For example, MiniDLNA uses
"audio/x-dsd".

When switching to another song manually, the player checks if the
decoder is already decoding that song; if so, it will attempt to reuse
it by seeking it to the new position.  That however fails if the
decoder is not seekable (e.g. a radio stream) which leaves the user
unable to switch to that song with the bogus error message "Not
seekable".

This addresses two problems:

1. the libFLAC write callback had to send an error status to its
caller when SubmitData() returned a command; this disrupted libFLAC
and the resulting command could not be used for anything;

2. the libFLAC function FLAC__stream_decoder_seek_absolute() also
calls the write callback, but its result cannot be used, because
seeking is still in progress, so we lose all data from one FLAC frame.
By moving the SubmitData() call until after CommandFinished(), we
avoid losing this data.  This fixes another part of #113

See code comment.

Instead of passing whole chunks to the MusicPipe and checking the
end_time after each chunk, truncate the last chunk if it would exceed
the end_time.  This requires keeping track of the absolute PCM frame
number.

This fixes a problem with gapless CUE song transitions: a small part
of the following song was always played twice.

Closes #113

Only _WIN32 is defined by the compiler, and WIN32 is not standardized
and may be missing.

Closes #169

Work around -Werror=catch-value.

Tremor decoder is unusable since commit 2ee43c40. Sound is distorted to
the point where it's nothing but noise.

The data from vorbis_synthesis_pcmout() needs to be scaled and
clipped for 16 bit sample size. For reference see
http://lists.xiph.org/pipermail/tremor/2010-April/001642.html and
http://lists.xiph.org/pipermail/vorbis/2006-October/026513.html.
Signed-off-by: Marcin Jurkowski <marcin1j@gmail.com>

If an early exception gets caught (e.g. from
AllocatedPath::FromUTF8Throw()) before
DecoderControl::CommandFinishedLocked() is called, the decoder thread
would go in an endless loop, because DecoderCommand::START is still
set.

Closes #118

GME starts all track indexes at zero, but subtune prefixes
start at one. This fixes an off-by-one error during track
enumeration.

ffmpeg plugin: when decoded stream duration is unavailable, attempt fallback to container duration (fix MusicPlayerDaemon/MPD#110)

Addresses #82.

Previously, the ffmpeg decoder only checked for the "generic"
MusicBrainz metadata keys used in other metadata container formats.

Add ffmpeg decoder support for *.adx files (Sega game console)

Closes #60

This eliminates some overhead, because the compiler doesn't need to
consider these functions throwing.

Fixes a potential crash bug which is actually unreachable, because the
"pcm" plugin is never invoked when there is no (matching) MIME type.

After a seek failure, the buffer may still be full, and then
FillBuffer() aborts with assertion failure.

https://bugs.musicpd.org/view.php?id=4665

This repairs the damage to commit 74dbaade done by commit
b3f5b493

https://bugs.musicpd.org/view.php?id=4656 describes a crash due to
division by zero because frame.samples==0.  This should never happen,
but apparently can happen after seeking.  The best we can do is to
just ignore this frame.

https://bugs.musicpd.org/view.php?id=3876

From the avformat_open_input() API documentation:

 "Note that a user-supplied AVFormatContext will be freed on failure."

https://bugs.musicpd.org/view.php?id=4607

The libWavPack documentation says:

 "After a FALSE return the file should not be accessed again (other
 than to close it); this is a fatal error."