Add mpris module

Uses libplayerctl to use the MPRIS dbus protocol to query, listen and
control media players.

Signed-off-by: Robert Günzler <r@gnzler.io>

include/factory.hpp

@@ -41,6 +41,9 @@
 #ifdef HAVE_DBUSMENU
 #include "modules/sni/tray.hpp"
 #endif
+#ifdef HAVE_MPRIS
+#include "modules/mpris/mpris.hpp"
+#endif
 #ifdef HAVE_LIBNL
 #include "modules/network.hpp"
 #endif