allow editing object's role in a relation directly on the object

[aceman]

1. Select an object
2. The tags pane shows its tags and in the second half shows which relations this object belongs to.
3. There is relation type/name, role in the relation, position in the relation

What currently happens:
I do not see a way to change the role of the currently selected object in the relation I select in this pane. I need to double-click the relation to open relation editor, locate the object again (may be hard due to the not always working highlight (only works on every other row)) and then change the role and close the relation.

Expected way:
Double click the role field and edit the role name.
It a free text object, isn't it? Or is there any logic that would need to be duplicated from the relation editor?

[aceman]

This was already implemented in another ticket or changeset