Refactor Optimizer ordering
  - create enum with the different steps named
  - unify numbering scheme
  - deploy enum to all places where int level was used
  - add passN enum so you can jump to a Pass when calling addPlan

useIndexForSort:
  - remove inline deletion of dependend nodes of our (removed) sortnode
  - redirect to pass #5 so now possible obsolete CalculaionNodes are removed by the removeUnnecessaryCalculationsRule
useIndexForSort:
  - redirect to pass #5 here too, so now possible obsolete CalculaionNodes are removed by the removeUnnecessaryCalculationsRule
SortNode optimizations: adjust tests to another rule needed to remove the SortNodes dependency.