Password plugin made compatible with modern Virtualmin

Added a new username format in Virtualmin driver,
which works for default Virtualmin settings where
username is user.postfix and domain is taken from
email address.

Example:
email - info@goodcoffee.com
login - info.goodcof

plugins/password/drivers/virtualmin.php

@@ -48,6 +48,10 @@ class rcube_virtualmin_password
             $pieces = explode("_", $username);
             $domain = $pieces[0];
             break;
+		case 8: // domain taken from alias, username left as it was
+			$email = $rcmail->user->data['alias'];
+			$domain = substr(strrchr($email, "@"), 1);
+			break
         default: // username@domain
             $domain = substr(strrchr($username, "@"), 1);
         }