Blocks PLANNER-2599. At this moment, problem changes are not incremental.

For example, in the Task Assigning example, doing a PC that adds a task while solving (click Produce) works because each such PC resets the working solution on the score director and the score is calculated from scratch.

With PLANNER-2599, the solution reset will be skipped. Adding or removing a task might affect the init score. This has to be accounted for in AbstractScoreDirector's afterProblemFactAdded/Removed() (when Task is not a planning entity) as well in afterEntityEntityAdded/Removed() (when Task is a shadow planning entity).