Adds itunes vol command.

Adds itunes vol, which takes an argument from 0 to 100 to set the
volume from the shell.

plugins/osx/osx.plugin.zsh

@@ -174,12 +174,16 @@ function itunes() {
 		next|previous)
 			opt="$opt track"
 			;;
+		vol)
+			opt="set sound volume to $1" #$1 Due to the shift
+			;;
 		""|-h|--help)
 			echo "Usage: itunes <option>"
 			echo "option:"
 			echo "\tlaunch|play|pause|stop|rewind|resume|quit"
 			echo "\tmute|unmute\tcontrol volume set"
 			echo "\tnext|previous\tplay next or previous track"
+			echo "\tvol\tSet the volume, takes an argument from 0 to 100"
 			echo "\thelp\tshow this message and exit"
 			return 0
 			;;
@@ -190,4 +194,3 @@ function itunes() {
 	esac
 	osascript -e "tell application \"iTunes\" to $opt"
 }
-