Fix error in parsing for MergeColumnStore
Add json test for ColumnStoreMerge
Add test for column store merge with index.
Test needs some more work. IndexAwareMerge needs some rework
because a deltaIndex is necessary in the current implementation
Add some documentation. Replace creation of mutableVerticalTable
Correct some comments. Add some more comments
Adjust some comments
Merge branch 'indexAwareMerging' into indexAwareMergingPerformance