audio::mpd gained ipv6 support

when i got a bug report asking for ipv6 support in audio::mpd, i didn't know where to start, and put it aside... but since i fixed quite a few test bugs in audio-mpd, i thought i could give a try at supporting ipv6.

and it proved quite easy in fact, with io::socket::ip which is a drop-in replacement for io::socket::inet... and thus, by changing 3 strings in audio-mpd, it is now ipv6 enabled - neat!

so, enable ipv6 on your software with the following one-liner:
$ ack -l 'IO::Socket::INET' | xargs perl -pi -E 's/IO::Socket::INET/IO::Socket::IP/g'
easy, uh? who said ipv6 was difficult? :-)