Version 0.15

+ Implemented the 'New' (Xml file) of the menu.
+ Prepared right-click actions to work on specific treeViewer elements.
Requirement for right-click: (MinOccurs=0 & MaxOccurs="unbounded")
+ Added 'MinOccurs=0' in the material element inside the
XSDValidator.xsd,
to allow right-click on all multiple-infinite elements.
+ Made use of 'default' values from XSD.
+ Renamed the 'Show all optional items' to 'Show all items'.
+ Updated the 'Show all items' to ignore default values.
+ Refactored class ElementItem & added error handling.
+ Refactored XSD Handler.
+ General Refactor.