review fit options (expose to Py, document?)
Under Fit/Option, we have quite some code to handle minimizer options. As far as I see, this machinery is only used by a few dedicated tests. We should review whether it can/should be simplified. Then it should be exposed to Python and GUI, and also be used in functional tests.
In the meantime, I will disable the standlone Rosenbrock test, which makes no sense without well chosen tolerances.