Bug fixes

* Makes sure the new grid object handles are handle object (not double)
* Fixed to add new elements in the order as given in H
Improvement

Hidden axes object with a visible child is now treated as visible
Bug fix

Fixed Elements validator
New member function: permute_elements

Used in set.Elements to sort Elements in the same order as given.
Bug fix & feature improvement

Fixed ElementHieghtFixed & ElementsWidthFixed to appear as column vector
Improved set.Elements to keep the objects order as given.
Bug fix

Fixed the behavior during setting Visible Property during openvideo()
and closevideo() functions
Split getCounterFormat from setcounterformat

getCounterFormat public function is created to expose the Frame Counter
Format string, and setcounterformat() now calls getCounterFormat to
acquire the format string.
Bug fix

Fixed Visible property handling