Fix for PHP7.0

[cris1]

This adjustment fixed the "PHP Fatal error: Uncaught Error: Function name must be a string in Ajax.php" for me running PHP7.0

[Wild1145]

Made this change manually and working perfectly.

[ooooyeahbabe]

$output = $lg->$_GET['cmd']($_GET['host']);
Change to
$output = $lg->{$_GET['cmd']}($_GET['host']);