[401659] New filters and trees under groups

[401659] New filters and trees under groups

Display the tree structure of the model below each group.
Add new filters :
* Identical elements : hide elements with no differences
* Pseudo conflicts elements : on a 3-way comparison, hide elements that
has been made on both side.
* Pseudo delete conflicts elements : on a 3-way comparison, hide deleted
elements that has been made on both side.
* Sub diff elements : hide differences under differences.
* Uml refined elements : hide all uml elements refined by another diff.
* Diagram (Gmf) refined elements : hide all gmf elements refined by
another diff.
Remove filters : Addes, Removes, Changed, Moved
Remove Group : By Metaclass

Bug: 401659

Change-Id: I97f4bcf6a2f4dc4fadec42a55c6b8adec574f536