..F....... [ZBX-4785] Improve form data sending to server by using JSON for some form elements.
- Change CTweenBox to store and send value using JSON.
- Implement jQuery plugin "setJsonOnChange" that when applied to some element with .val() stores its content into specified target input, JSONed. 
- Add method CComboBox::serializeToVar().
- Change popup_right.php to add only 1 hidden input with JSONed value instead of many separate hidden inputs.