Provides practical access to descendant courses of a metacourse
A descendant course (child) is a normal course from which the current course gets some of his enrolments by propagation.
The course descentants block gives in a block a fast link list to those courses, depending if the current user has effective enrolment in it.
When meta-courses are used as subparts of a training program, than this block used in the meta-course allows a fast browse up to a surrounding enrolment course.