fehmpytest for dispersion

[millerta]

Xiang has developed a good test for dispersion.
It requires a an analytic evaluation for correctness which fehmpytest is not currently setup for.
Xiang will provide the files, the python script that checks results, and documentation.

[millerta]

Xiang copied the dispersion problem here, using FEHM V3.4.2lbUbuntu16
/project/salt/xhuang/dispersion