SMG: abstract lists of elements with the same color
SMG: abstract lists of elements with the same color
Add color to list objects. Use the color of the object the list abstracts. Allow finding samely colored objects to abstract into a list. Update test results: colored lists can be abstracted now.
SMGSingleLinkedList: refactor constructors.
SMGDoublyLinkedList: refactor constructors. Use #forTesting instead of public constructor with 6 indistinguishable integers in line. Use new constructor with better parameters outside of the tests. #copy(int, int) is not very good in this regard, but use it, too.