Calculate collection grades/stats when all child-assignments have 0 weight.
0-weight assignments are normally ignored in grade calculations. In case all children assignments have zero weight, we can treat the children as having equal weights (i.e. 1.0), so we can calculated aggregated values such as the mean grade, and calculate started, passed and completed state.
Submitted by Elmer van Chastelet on 23 March 2019 at 21:45