* Extended IFailureMechanism with IObserver interface. * FailureMechanismSectionsContext now delegates IObserver implementation to wrapped failure mechanism. * ReferenceLineImporter now clears failure mechanism sections when replacing a reference line. Related to Issue [WTI-365] git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@2373 5a3db67b-de53-47b5-99c8-a1c30a6650e2