Version 0.19

+ Added NewName user input validation. The NewName must be unique.
+ Fixed 'Save' data to XML.
+ Removed XmlNode from project.
+ Implemented ConvertToXml(Item) method in XmlParser.
+ Fixed reference lists updating on controls.
+ Saving handles properly Units, XUnits, References and Keywords.
+ Fixed Variable Table GetValue bugs.
+ Fixed some broken links.
+ Code cleanup.