This plugin controls the playback of mpris-enabled applications in this device,
commanded by its counterpart in the other device that acts as a remote control.
That means both plugins are not symmetrical.
This plugins receives and sends packages with type kdeconnect.mpris.
It keeps a list of detected players it can control via MPRIS. When it receives
a package that contains the boolean "requestPlayerList" set to true, it will
send back the list of players in an array named "playerList". If a new player is
detected or a known one dissappears, it should also send this list. Note that
players are identified only by its name (its MPRIS Identity), so there can not
be two players with the same display name.
This plugins also reports the current song, extracted from MPRIS Metadata. It
should send it when it changes or when receiving a package containing a boolean
"requestNowPlaying" set to true.
The remote devices can send packages with commands to one of the players. Those
packages will contain a string "player" with the name of the player they want to
command and a string "action" with the name of an MPRIS call (like "Play",
"Next"...).
This plugin can also control the system volume. The peer device can send a
package with "requestVolume" set to true to ask for the current volume, or send
a package with "setVolume" set to an integer in the range [0,100] to change it.
