added distants notifications and devices availability warning

class/availibility.php

@@ -0,0 +1,31 @@
+<?php
+	<?php
+class availability
+{
+	// by default all devices are listening for availability
+
+	// callback fonction. Is called with these 4 parameters
+	public function callBack($topic, $fn, $param, $value)
+	{
+		global $devices, $indexDevices, $notificationMethods;
+		switch($param)
+		{
+			case "availability":
+				if ($value != "online")
+				{
+					//your code here
+					logger("Device: " . $topic . "/" . $fn . "is offline");
+				}
+				break;
+		}
+		echo _("notification received from MQTT") . EOL;
+		//echo $param . "=> " . $value . EOL;
+	}
+}
+
+$hooks["availability"] = new availability;
+?>
+
+
+
+?>