MWE master-stepper

[artofscience]

Create a MWE that does master-stepping as follows:

2. Run master stepper that initiates two steppers with arclength in both directions (positive and negative lambda) from a user-specified point with eigenvaluechange termination and load termination.
3. Master stepper identifies potential visiting of critical point twice within slave steppers.
4. Store the points where eigenvalue has changed.
5. Run dynamic solver from those points in both directions (speed or state perturbations along zero-stiffness modes).