A simple class to hold the output data from the PTC task.
The dataset is made up of a dictionary for each item, keyed by the
amplifiers' names, which much be supplied at construction time.
New items cannot be added to the class to save accidentally saving to the
wrong property, and the class can be frozen if desired.
inputVisitPairs records the visits used to produce the data.
When fitPtcAndNl() is run, a mask is built up, which is by definition
always the same length as inputVisitPairs, rawExpTimes, rawMeans
and rawVars, and is a list of bools, which are incrementally set to False
as points are discarded from the fits.
Definition at line 145 of file ptc.py.