Add base class ChartStyle to the chart style objects, containing an IsEditable property. Related to Issue [WTI-1315]git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@11203 5a3db67b-de53-47b5-99c8-a1c30a6650e2Former-commit-id: be23e5a0c2339b924336a9aa0288dd0fb16a82bdFormer-commit-id: 2fc3b766745f87b041e73d5d8968050860fa17c6