get_roots_rect fails to return roots obtained with numpy.roots from the same polynomial.

[petersbingham]

The issue can be demonstrated using the additional test cases added to the fork here:
https://github.com/petersbingham/potapov_interpolation/blob/Potapov_PolyRootTests/Potapov_Code/tests/tests_Roots.py

eg:

test_Poly_Roots(19, printRoots=True, printPolys=False, printParams=False, doubleOnWarning=False)
test_Poly_Roots(32, printRoots=True, printPolys=False, printParams=False, doubleOnWarning=False)

When running these examples some stats are printed and then a list of roots (in the left column) obtained using numpy.roots and then another list obtained using get_roots_rect. The numbers in the right column (beside the roots) are the results of plugging the root back into the function (so obviously expect to be close to zero).

With N=19 above the numpy root at -0.830414981861-0.869004835643j is not returned.
With N=32 several roots appear missing.

[petersbingham]

Fixed in: https://github.com/petersbingham/pydelves