mst_groupsort will sort the MSTrace segments in a MSTraceGroup first on the source name (as returned by
mst_srcname), then on start time, then on descending end time, and finally on sample rate. The quality
flag, passed directly to mst_srcname, controls the addition of the quality indicator to the source name
and thus the addition of sorting on the quality indicator (but only if the MSTrace has an associated
quality, see mst_srcname(3) for more details).
mst_groupheal will attempt to heal MSTrace segments in a MSTraceGroup if they fit within the specified
time and sample rate tolerance (timetol and sampratetol respectively). This is useful when, for whatever
reason, the MSTraceGroup has separate MSTrace segments which belong together. This usually only happens
when data is added to a MSTraceGroup in random data time order. Before attempting to heal the MSTraces
the MSTraceGroup will be sorted using mst_groupsort.
If sampratetol is -1.0 the default tolerance of abs(1-sr1/sr2) is used. If timetol is -1.0 the default
time tolerance of 1/2 the sample period will be used.