Updated musicpd to 0.20.2.

ver 0.20.2 (2017/01/15)
* input
  - alsa: fix crash bug
  - alsa: fix buffer overruns
* decoder
  - flac: add options "probesize" and "analyzeduration"
* resampler
  - libsamplerate: reset state after seeking
* output
  - fix static noise after changing to a different audio format
  - alsa: fix the DSD_U32 sample rate
  - alsa: fix the DSD_U32 byte order
  - alsa: support DSD_U16
  - recorder: fix error "Failed to create : No such file or directory"
* playlist
  - cue: fix skipping songs

ver 0.20.1 (2017/01/09)
* input
  - curl: fix crash bug
  - curl: fix freeze bug
* decoder
  - wavpack: fix crash bug
* storage
  - curl: new storage plugin for WebDAV (work in progress)
* mixer
  - alsa: normalize displayed volume according to human perception
* fix crash with volume_normalization enabled

ver 0.20 (2017/01/04)
* protocol
  - "commands" returns playlist commands only if playlist_directory configured
  - "search"/"find" have a "window" parameter
  - report song duration with milliseconds precision
  - "sticker find" can match sticker values
  - drop the "file:///" prefix for absolute file paths
  - add range parameter to command "plchanges" and "plchangesposid"
  - send verbose error message to client
* input
  - curl: fix memory leak
* tags
  - ape, ogg: drop support for non-standard tag "album artist"
    affected filetypes: vorbis, flac, opus & all files with ape2 tags
    (most importantly some mp3s)
  - id3: remove the "id3v1_encoding" setting; by definition, all ID3v1 tags
    are ISO-Latin-1
  - ape: support APE replay gain on remote files
  - read ID3 tags from NFS/SMB
* decoder
  - improved error logging
  - report I/O errors to clients
  - ffmpeg: support ReplayGain and MixRamp
  - ffmpeg: support stream tags
  - gme: add option "accuracy"
  - gme: provide the TRACK tag
  - gme: faster scanning
  - mad: reduce memory usage while scanning tags
  - mpcdec: read the bit rate
  - pcm: support audio/L16 (RFC 2586) and audio/x-mpd-float
  - sidplay: faster scanning
  - wavpack: large file support
  - wavpack: support DSD (WavPack 5)
  - wavpack: archive support
* playlist
  - cue: don't skip pregap
  - embcue: fix last track
  - flac: new plugin which reads the "CUESHEET" metadata block
* output
  - alsa: fix multi-channel order
  - alsa: remove option "use_mmap"
  - alsa: support DSD_U32
  - alsa: disable DoP if it fails
  - jack: reduce CPU usage
  - pulse: set channel map to WAVE-EX
  - recorder: record tags
  - recorder: allow dynamic file names
  - sndio: new output plugin
* mixer
  - null: new plugin
* resampler
  - new block "resampler" in configuration file
    replacing the old "samplerate_converter" setting
  - soxr: allow multi-threaded resampling
* player
  - reset song priority on playback
  - reduce xruns
* write database and state file atomically
* always write UTF-8 to the log file.
* remove dependency on GLib
* support libsystemd (instead of the older libsystemd-daemon)
* database
  - proxy: add TCP keepalive option
* update
  - apply .mpdignore matches to subdirectories
* switch the code base to C++14
  - GCC 4.9 or clang 3.4 (or newer) recommended

(wiz)