The user manual specifies "encoder", which is consistent with other
output plugins.  "encoding" should be deprecated.

The ScopeExit library uses C++11 initializers, which gcc 4.6 does not
support.  Let's kill support for this ancient incomplete C++11
compiler, nobody should be using it anymore.

A complete list which replaces the incomplete list in the mpd.conf
manpage.

These are other popular clients. In particular, VLC is available on
mobile devices.
Signed-off-by: Ben Boeckel <mathstuf@gmail.com>

The Release Track Id uniquely identifies a recording on a release - that
is, even if a recording appears twice on a release (meaning that the
combination of recording and release id are not enough to figure out
which one it is), the release track id will allow differentiating the two.

The tag names are taken from
https://musicbrainz.org/doc/MusicBrainz_Picard/Tags/Mapping

The standard has been renamed since the early draft that was
implemented in MPD.

Fix incorrect description of the "songs" field and add missing
"albums" field.
Signed-off-by: Joachim Fasting <joachifm@fastmail.fm>