Fixes to installation of neatpp

[mbkumar]

This PR installed neatpp inside src/neat, which is picked up by python setup.py framework. Updated the imports to reflect the new location.

[rogeriojorge]

The CI is failing. For some reason it is not able to find the neat.neatpp package

import neat
Traceback (most recent call last):
File "", line 1, in
File "/NEAT/src/neat/init.py", line 7, in
from .neatpp import gc_solver_qs
ModuleNotFoundError: No module named 'neat.neatpp'

[rogeriojorge]

I was able to do the purpose of this PR in
#5
by removing the VMEC module. The PR is based on this one.

Thank you for all your help @mbkumar