Introduced the additional columns
The user can now set the "Not Set" Value explicitly
Abstraction of the AdditionalColumn
NoChangeColumns are now also working
Improve of API and simplified use
Start of handling with MultiEdit
We nearly support multiedit
Editing of multiple objects is now possible
Nearly every control type supports multi editing
When user changes content of form, the checkboxes for the additonal columns will be cleared
Fixed issue #110 (Xml Rootnode)