Additional plugins for GMPC.

Requires gmpc, gob2, json-glib, and optionally several others:
avahi, awn, lirc, microhttpd, and webkitgtk.
Some of these are available at SlackBuilds.org. If you have any
of these and would like to enable the plugin, the variables are
as follows: AVAHI AWN LIRC MSERVER WIKIPEDIA

For example, if you have avahi and lirc, you would do this:
	AVAHI=yes LIRC=yes ./gmpc-plugins.SlackBuild