McLachlan should not checkpoint the constraint variables if they have only one timelevel
Issue #1325
new
ML_BSSN_Helper currently checkpoints the constraint variables even if they only have one timelevel. This is because it incorrectly assumes that the number of timelevels for these variables is given by the "timelevels" parameter, when in fact it is given by the "other_timelevels" parameter.
Keyword: McLachlan