Added 'MPRIS' module

This commit adds the ability to display status information for MPRIS
compatible music players.

Closes #53

doc/meson.build

@@ -34,6 +34,9 @@ endif
 if plugin_mpd_enabled
   plugin_pages += ['yambar-modules-mpd.5.scd']
 endif
+if plugin_mpris_enabled
+  plugin_pages += ['yambar-modules-mpris.5.scd']
+endif
 if plugin_i3_enabled
   plugin_pages += ['yambar-modules-i3.5.scd']
   plugin_pages += ['yambar-modules-sway.5.scd']

doc/yambar-modules-mpris.5.scd

@@ -0,0 +1,95 @@
+yambar-modules-mpris(5)
+
+# NAME
+mpris - This module provides MPRIS status such as currently playing artist/album/song
+
+# TAGS
+
+[[ *Name*
+:[ *Type*
+:< *Description*
+|  state
+:  string
+:  One of *offline*, *stopped*, *paused* or *playing*
+|  shuffle
+:  bool
+:  True if the *shuffle* flag is set
+|  repeat
+:  string
+:  One of *none*, *track* or *paylist*
+|  volume
+:  range
+:  Volume in percentage
+|  album
+:  string
+:  Currently playing album
+|  artist
+:  string
+:  Artist of currently playing song
+|  title
+:  string
+:  Title of currently playing song
+|  file
+:  string
+:  Filename or URL of currently playing song
+|  pos
+:  string
+:  *%M:%S*-formatted string describing the song's current position
+   (also see _elapsed_)
+|  end
+:  string
+:  *%M:%S*-formatted string describing the song's total length (also
+   see _duration_)
+|  elapsed
+:  realtime
+:  Position in currently playing song, in milliseconds. Can be used
+   with a _progress-bar_ particle.
+
+# CONFIGURATION
+
+[[ *Name*
+:[ *Type*
+:[ *Req*
+:< *Description*
+|  identities
+:  list of string
+:  yes
+:  A list of MPRIS client identities
+
+# EXAMPLES
+
+```
+bar:
+  center:
+    - mpris:
+        identities:
+          - "spotify"
+          - "firefox"
+        content:
+          map:
+            conditions:
+              state != offline && state != stopped:
+                - string: {text: "{artist}", max: 30 }
+                - string: {text: "-" }
+                - string: {text: "{title}", max: 30 }
+```
+
+# NOTE
+
+The 'identity' refers a part of your clients DBus bus name.
+You can obtain a list of available bus names using:
+
+```
+Systemd:   > busctl --user --list
+Playerctl: > playerctl --list-all
+Libdbus:   > dbus-send --session --print-reply --type=method_call --dest='org.freedesktop.DBus' /org org.freedesktop.DBus.ListNames ... | grep 'org.mpris.MediaPlayer2'
+```
+
+The identity refers to the part after 'org.mpris.MediaPlayer2'.
+For example, firefox may use the bus name
+'org.mpris.MediaPlayer2.firefox.instance_1_7' and its identity would be
+'firefox'
+
+# SEE ALSO
+
+*yambar-modules*(5), *yambar-particles*(5), *yambar-tags*(5), *yambar-decorations*(5)