MODFLOW-6 support

[maxwnewcomer]

Would love to have an extension to NWTOPT for modflow-6. Mike already has the beginnings, but would be great to get this done after getting the main nwtopt stuff done.

[mnfienen]

Here's the branch I'm working on in my fork: https://github.com/mnfienen/NWTOPT/tree/mf6

Hope to make more progress this week

[maxwnewcomer]

Looks great so far, seems like all you'll have to do is convert the ies params to file on the worker end of things. This is done in objective.py and is kind of a PITA to map them (the dictionary that the worker receives is a little confusing). A good testing setup would be to run the hyperopt-mongo-worker (found in environment bin) locally and start a fake optimization. Note that objective.py needs to be in the same directory as the hyperopt-mongo-worker for it to all work.

[maxwnewcomer]

Going to work on this implementation after Issue #21 is resolved.