Support for menubar attribute to the :func:`anchor_popup()`

Now the menubar can be set to yes with anchor_popup() by adding new attribute array element 'menubar' => 'yes' 
The list of all available attribute for anchor_popup() function will be 
$atts = array('width' => '800', 'height' => '600', 'scrollbars' => 'yes', 'menubar' => 'no', 'status' => 'yes', 'resizable' => 'yes', 'screenx' => '0', 'screeny' => '0');