Checks loops for intersection and direction. If the cycle is placed at an even level of the tree, and the direction is clockwise, it will be marked as invalid (it will not be displayed). To change direction to the correct one, use balanceTree(). If a cycle intersects with another cycle, the cycle with a higher index will be marked as invalid (not drawn). Loops that have been marked as invalid but have the correct direction and no intersections will be marked as valid and will be drawn again. 

eOk if check and changes are successful, or eInvalidInput if getMPolygonTree() did not generate a tree.