Implemented ISurfaceLineUpdateStrategy for the surface line importer: - Adjusted tests, introduced an internal TestSurfaceLineUpdateStrategy to be independent of the concrete implementations - Renamed interface for consistency reasons: name is now consistent with the soil model equivalent - Hooked up the strategy with the PipingPlugin, AddNewDemoAssessmentSectionCommand and DataImportHelper Related to Issue [WTI-1075] git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@8129 5a3db67b-de53-47b5-99c8-a1c30a6650e2