The NodeEvaluation makes it difficult to use a course node in the
learning path access concept. So it is refactored to a minimum extent,
so that it can covering the previous functionality.
As a replacement a new security callback and a new tree node type is
introduced.

New concept to wire the course node edit controllers.
Applied to single page course node.

Calculation of the learning path status of the course nodes.
First draft of a GUI to visualize the learning path of a course participant.

Users have to select the configuration when creating a new course.