This is based on the discussion in PR #76.

This can be used to extend the idea of PR #76. If a test is called with tryNonGroupElements := true, then currently random elements are created that have a very low probability to pass ValidateHomomInput (see #98). RandomValidInputForHomomorphismOfRecogNode should create elements that always pass ValidateHomomInput but will usually not be in the group that is represented by the recognition node.