BREAKING: AddLabelSetLayer is replaced by ReplaceGroupLabels and RemoveLayer by RemoveGroup

Why: AddLabelSetToLayer was to complicated due to unecessary features. The part that is not
provided by other methods is now provided by ReplaceGroupLabels.

How to adapt:
(1) Use ReplaceGroupLabels if you want to exchange labels. To generate new layers use AddLayer.
(2) Use RemoveGroup instead of RemoveLayer.