interfaces: merge netgraph progress from master (not enabled)

Makefile

@@ -67,6 +67,7 @@ CORE_DEPENDS?=		apinger \
 			miniupnpd \
 			mpd4 \
 			mpd5 \
+			ngattach \
 			ntp \
 			openssh-portable \
 			openvpn \

src/etc/inc/interfaces.lib.inc

 <?php
 
 /*
-    Copyright (c) 2015 Franco Fichtner <franco@opnsense.org>
+    Copyright (c) 2015-2016 Franco Fichtner <franco@opnsense.org>
     All rights reserved.
 
     Redistribution and use in source and binary forms, with or without
@@ -199,3 +199,18 @@ function legacy_interface_details($intf)
     }
     return $result;
 }
+
+function legacy_netgraph_attach($ifs)
+{
+	mwexecf('/usr/local/sbin/ngattach %s', array($ifs));
+}
+
+function legacy_netgraph_detach($ifs)
+{
+        mwexecf('/usr/sbin/ngctl msg %s: detach', array($ifs));
+}
+
+function legacy_netgraph_rename($tmpifs, $ifs)
+{
+        mwexecf('/usr/sbin/ngctl name %s: %s', array($tmpifs, $ifs));
+}