Added \Core\Form\Form class to handle a collection of \Core\Config\Fields.
Added some validation stuff into \Core\Config\Field.
Fixed a bug when we load parents of a element that is not in a tree
Added value validation check into \Admin\ObjectCrud class
Fixed root position bug
Added a label class for ka.Select field.
Added `disabled` field option
Added type into the nodeCrud list and added visibility condition to the content tab.
Some bugfixes and layout adjustements