harden solution cloner test for DeepPlanningClone on Solution
docs: add more section id's (and rename some titles)
solution cloner: do not clone Collection or Map elements if they don't need to be cloned. Avoid unneeded key cloning such as for Map<String, PlanningEntity>.
PLANNER-260 Cloner should be able to deep clone entities in Map<String, List<PlanningEntity>> too