Added tests for AssertContextMenuStripContainsItem in TestHelper. Extended AssertContextMenuStripContainsItem with possibility to supply an expected enabled state. Disabled menu items in FailureMechanismNodePresenter's and PlaceholderWithReadonlyNameNodePresenter's context menu which have no functionality yet. Reordered ProjectTreeView's ContextMenu to match the one of FailureMechanismNodePresenter. Related to Issue [WTI-172] git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@950 5a3db67b-de53-47b5-99c8-a1c30a6650e2