Allow "unsetting" non-critical keyword arguments to FlorisModel.set()

[misi9170]

Provide ability to "unset" certain elements of the FlorisModel

When keyword arguments are set on the instantiated FlorisModel using the set() method, they are remembered. To override a previously set variable, one most override that variable with a new call to set(). However, for some arguments, in particular, heterogeneous_inflow_config, it would be nice to be able to "unset" or forget a previous setting. FlorisModel currently has no way to do this, since passing None (e.g. fmodel.set(heterogeneous_inflow_config=None)) simply means using the previously set case.

Proposed solution

A possible solution would be to allow a special (unambiguous) argument to be passed to keywords that could be "unset" in order to trigger the unsetting action. For example, fmodel.set(heterogeneous_inflow_config=-1) or fmodel.set(heterogeneous_inflow_config=False).

Alternatives considered

A second alternative is to define new methods on FlorisModel for the unsetting procedure. This is actually something that we already have for unsetting previously set control actions: FlorisModel.reset_operation(). However, if we go down this route, we'll need a new method for each non-critical variable, which seems a little annoying (especially if these changes are to be reflected in UncertainFlorisModel and ParallelFlorisModel).

Current workaround

For now, users can "forget" things by simply reinstantiating their FlorisModel from scratch.

Additional context

I'd like a general solution here, which requires identifying which of the arguments to FlorisModel.set() are valid candidates for "unsetting". I would think at least the following:

• heterogeneous_inflow_config
• Control setpoints (yaw_angles, power_setpoints, awc_modes, awc_amplitudes, awc_frequencies, disable_turbines)
• possibly wind_data, turbine_type and turbine_library_path, solver_settings

[misi9170]

#959 may be related

[misi9170]

A similar issue has just come in in #1016; there is currently no way to "unset" the wind_data (since providing wind_data=None to FlorisModel.set() just retains the existing wind_data), so warnings are constantly raised about Deleting stored wind_data information when the wind_speeds, wind_directions, and turbulence_intensities are set directly onto a FlorisModel object that has a non-None wind_data attribute.