[425799] Add dependency : org.eclipse.uml2.uml

Change-Id: Id0337ca982d936c011114e0a9da4841b4908abb5
Signed-off-by: marwa rostren <mrostren@obeo.fr>
[425799] Use the Resource instead of IResource to initiate the exported file
content.

Change-Id: I750138bbdc7109973d9299039ddb7a4431b57f93
Signed-off-by: marwa rostren <mrostren@obeo.fr>
[425799] Propagate checked/uncheked to adjacent tree.

This propagates checked/uncheked to the element and to its ancestors in
the adjacent tree.

Change-Id: I61ac6e7e650fbbacbfb72b6553cfe0417e176425
Signed-off-by: marwa rostren <mrostren@obeo.fr>
[425799] improve elements selection performance

Change-Id: Id09554fe56df79b490e0da5e2984607ad10a3c36
Signed-off-by: marwa rostren <mrostren@obeo.fr>