Introduced PointBasedChartData to reduce code clones. Refactored ChartDataConverter to improve robustness (prevented having to hard-cast ChartData in several places). Refactored ChartDataNodePresenter to fix open/closed principle violation. Related to Issue [WTI-272] git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@1728 5a3db67b-de53-47b5-99c8-a1c30a6650e2