gui: forms: add possibility to mark properties as readonly in forms
gui: marked datachangedlistener as a functional interface
gui: wdatetextfield: replaced the great jdatepicker with own fork
gui: widgets: implemented setEnabled() to work as expected
gui: forms: make use of readonly flag in annotation.
gui: forms: implement requestFocus() to work as expected.
gui: widgets: AbstractWComponent delegates setEnabled() to childs
gui: build: replace jdatepicker with own fork
eclipse classpath update