Iso metrics

This branch includes code for computing ISO metrics APCER and BPCER. Please merge it to master.

Mentioned in commit 6b07fba1

Status changed to merged

@sbhatta is there any reason your created a class for it? Why didn't you just create several methods?

Legacy reasons. When I first started working on it I made a class that needed to be initialized correctly before use. Later on I simplified things, to the point where a class is not really necessary, but since it's there, I left it like that.

@sbhatta could you please change it so that things are functions now? We don't want to refactor code in future and that is why I am picky about things.