New command: set iface name

FreeBSD has supported network interface renaming for some time now, and it is useful. I've written a patch for mpd 5.3 which allows it to rename the ng interfaces that it creates.

This patch adds a new command: set iface name <name>

Interface renaming is extremely useful when dealing with many network interfaces. Please consider integrating this patch (or the same functionality) into a future release mpd.

Thanks,
Aragon