Add a new algorithm for determining which direction of an optimisation scan to show

One feature of the TQHWWPlotter library is to compute and show an optimisation scan of a histogram, with identical binning. The scan is done in both directions, and one may choose (through the optScan.autoselect tag) to automatically select one of them to discard. The existing algorithm to make this decision would only discard one scan if it was lower than the other scan in every bin, which as far as I can tell is the case... almost never? I changed the algorithm to simply look at which scan has the highest maximum and discard the other.

When I test this on a set of histograms from my analysis, it makes the exact same decisions that I would, correponding to the directions of the cuts that are applied at a later stage.