first version of change_password interceptor (more see details)

- add stripLocalpart in helpers.php
- extend mxDatabase to update the password once validated

helpers.php

@@ -0,0 +1,18 @@
+<?php
+function stripLocalpart($mxid) {
+	$localpart = NULL;
+	if (!empty($mxid)) {
+		// A mxid would start with an @ so we start at the 2. position
+		$sepPos = strpos($mxid,':', 1);
+		if ($sepPos === false) {
+			// : not found. Assume mxid is localpart
+			// TODO: further checks
+			$localpart = $mxid;
+		} else {
+			$localpart = substr($mxid, 1, strpos($mxid,':') - 1 );
+		}
+	}
+	return $localpart;
+}
+
+?>