Update nrtest-swmm with mincdd_compare

[michaeltryby]

Discussing need for a more "rational" comparison criteria for benchmark results. epanet_mincdd_compare can be found here:

https://github.com/EPANET-Project/epanet-python/blob/dev/nrtest-epanet/nrtest_epanet/init.py

So if we wanted to run the mincdd we would need to add it to nrtest-swmm and rebuild. Then in the swmm-nrtestsuite repo update the test description files to call the new comparison routine. Then update the helper scripts with the tolerance we want probably 2 or 3 decimal places of precision.