The "sticker" command allows clients to query or manipulate the
sticker database. This patch implements the sub-commands "get" and
"set"; more will follow soon (enumeration), as well as extended
"lsinfo" / "playlistinfo" versions.
Over the years, a lot of commands have been added to MPD which were
documented only in the wiki
(http://mpd.wikia.com/wiki/Protocol_Reference). Merge all missing
commands from there.
The goal is to have one structured document which is the authoritative
protocol specification. The documentation which currently resides in
the wiki will be merged.
