DragonFlyBSD support added
make SIGUSR1 do nothing, so that killall -USR1 i3status will force an update

Sending SIGUSR1 will interrupt the nanosleep() and thus force a new
iteration of i3status’s output loop. The signal handler itself is empty.

Based on the question by ttjjss at
http://faq.i3wm.org/question/854/how-to-force-status-bar-update/
changing volume color from bad to degraded if muted
add mpd support to i3status