Add calibration accuracy plot to reports
Add a calibration plot to reports.py that generates a dFAP/FAP % error by nominal FAP plot with error bars.
Additionally, change interpolation scheme from linear across the entire set to nearest-neighbor. This should fix odd behavior previously seen in FAP calibration plots where points would extend off-diagonal in the space b/w 1 and the highest significance veto.
Edited by Rachael Huxford