Improved and documented interface of the AssignUnassignCalculations and GrassCoverErosionInwardsHelper. Moved AssignUnassignCalculations to Ringtoets.Common.Utils. Extracted classes from the AssignUnassignCalculations and GrassCoverErosionInwardsHelper classes. Started with implementation of the heightStructuresScenario view. Related to Issue [WTI-587] git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@5857 5a3db67b-de53-47b5-99c8-a1c30a6650e2