WHO should leave the client idle

Some clients seem to automatically poll for channel state

irc/commands.go

 			minParams:    4,
 		},
 		"WHO": {
-			handler:   whoHandler,
-			minParams: 1,
+			handler:         whoHandler,
+			minParams:       1,
+			leaveClientIdle: true,
 		},
 		"WHOIS": {
 			handler:   whoisHandler,