Checkpoint before testing new analytic continuation method
involving computing entire fibres.
Checkpoint for RiemannSurfacePath analytic continuation.

We're trying various techniques for analytic continutation.
This commit serves as a checkpoint for various branches
implementing these techniques.
Implement simple analytic continuation.

Analytic continuation now works (*). The technique
uses a combination of Taylor stepping to obtain an
approximate solution and then Newton iteration to
converge to the actual root of the polynomial.

(*) Some parameter playing needs to be done so the
implementation needs refinement.