Fix dependencies definition
Add drag and drop support for palette
Remove unnecessary methods
Delegate doSave and isDirty to included editors
Implement save method to create XML
Add actionBarContributor

* It allows redo and undo in Design Editor
Fix bug when section (e.g. properties) is null in model
Change design editor save method and dirty flag
Modify JAXB context depending on model type
Change editor's tabs labels

Design editor -> Designer
XML editor -> Source