When selecting linearization parents, allow only direct parents

[tudorache]

Currently, we allow the selection of any ancestor as a linearization parent.

After discussion with Can, we need to allow only the direct parents as linearization parent. Therefore, it is not necessary to display the tree of ancestors anymore, but a simple list.

This list should also provide the possibility to unset the linearization parent. Here is an example on how it is done on icat-demo:

[alexsilaghi]

its already done , I have to check in what branch the change exists.

[alexsilaghi]

We will replace the existing dialog , with a listbox.