Enhancement: Add a MPC/MPD Plugin

[pspiagicw]

Describe the feature you'd like

A MPD plugin showing the currently playing song. MPD is a very popular offline music server (https://www.musicpd.org/)

The plugin would query the local MPD server through the command line tool mpc. Would be a good complement to the existing spotify-tui plugin.

User Options

Just like the spotify-tui plugin, there would be a option to configure the mpc client output.

Rough implementation.

I already have a rough implementation that I use in my personal setup. It is a direct modification of the spotify-tui plugin.
I am willing to open a PR to discuss the implementation further.

I have attached a screenshot of my personal implementation.

[JannoTjarks]

Hi,

I created the Spotify tui plugin :D
Would be nice, if you push your code as git repo, because I am also using the mpd daemon. If you need help, just ask.

[pspiagicw]

Hi @JannoTjarks,

I have forked the repo and commited my changes (https://github.com/pspiagicw/tmux).
I have also opened a PR to merge my changes into the upstream repo.