Added log4j (previously)

Document for DecisionTreesBuilder updated. To follow - change of approach, give up creating and saving all the single tree files.
DecisionMaker calls the DecisionTreesBuilder when a condition of free fields from DecisionTreesSetting class is met.

No more loading trees.

This will be easier, as creation of the trees  with the conditions in DecisionTreesSettings class is quick and doesnąt require loads of memory.
DecisionMaker is no longer IBoardListener.

Changes to decision maker and DecisionTreesSettings regarding the number of free fields and the moment whent he decision tree gets built.

Tested with a GUI. Seems to block winning moves, but freezes at some point - need to investigate.
Fixed issue with decision tree creation: previously it was created only once and used thereafter. Now it's created whenever required - when best point is being found.