Added subnode to Hydraulische randvoorwaarden node. Moved some properties to the subnode. Added fold/collapse to node. Moved some testcases from node to subnode test class. Related to Issue [WTI-697] git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@4488 5a3db67b-de53-47b5-99c8-a1c30a6650e2