Use checkbox_obj.gif icon to produce SelectAll/DeselectAll icons

Change-Id: I0eece6e6bb2549d9c2546eabb93909af97291233
Signed-off-by: marwa rostren <mrostren@obeo.fr>
Use emf Resource instead of core IResource in the IValidatorExport

Change-Id: Ib44d6a2b12efb4b0beffbfd7273b069744ae3709
Signed-off-by: marwa rostren <mrostren@obeo.fr>
Tests cleaning/refactoring

Change-Id: I7e6c66ac7352b0bca404f7f9669c2c95984b14fa
Signed-off-by: marwa rostren <mrostren@obeo.fr>
Fix constraining tree select/unselect. This propagate select/unselect down to the result checkboxes.