Iterative heightchanger

Rewritten HeightChanger to follow an iterative approach using a Queue of active Positions. Also, the iterative approach makes more use of functional operators. As a result, the complexity of the method is greatly reduced without changing the behavior (verified through play-testing).

This became another pull request as to not interfere with the improvements of Fiero99. The improvements with regard to javadoc fixes and structural changes besides the `findAffectedByRaise` method (which has been renamed to just `findAffected` for brevity) are taken directly from the pull request by Fiero99.
This rule says, there is a chance that the set can be exact the size of the performanceCap and then be stopped. So in this case, the heighchanger will raise these 25 tiles and will leave the other tiles unaffected. This is a possibility to get a gap in the world, isn't it?!