import SPD.lib.leastsq_jacobian as lib_k in pmag.py causing issue due to SPD import in some environments

[Swanson-Hysell]

What command was run:

For some reason the

import SPD.lib.leastsq_jacobian as lib_k

in PmagPy is causing problems in some environments. It caused an issue for @maxwellbrown and I was just getting up an environment where I had the same issue.

The import is happening for the get_curve() function

What happened:

ImportError: cannot import name 'lib' from partially initialized module 'SPD' (most likely due to a circular import) (/Users/unimos/0000_Github/PmagPy/SPD/__init__.py)

PmagPy version: pmagpy-4.2.115