pwFitHistoryMergeFitSequences Merges all related fits of the fit history into fit sequences sharing the same fit sequence start time.
Two fit sequences may belong to the same fit settings, model and data sets: they belong to the same fit group. Function like pwFitSequenceAnalysis work on the last fit sequence unless specified otherwise. The function pwFitHistoryMergeFitSequences merges all fit sequences as far as possible, i.e. the number of fit sequences will be the same as the number of fit groups. This is done by assigning the earliest fit sequence start time to all fits belonging to the same fit group.