Added factory for creating calculator stub to use in tests. Related to Issue [WTI-1407]git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@11794 5a3db67b-de53-47b5-99c8-a1c30a6650e2Former-commit-id: c9860da9b089b06f31f177d75698e2d3fd2e7f21Former-commit-id: 976ccdc613341f11dd672cc79cae77d8ec128c01