Advanced spectral mismatch calculation

[adriesse]

Is your feature request related to a problem? Please describe. The spectral mismatch calculation from field spectral irradiance measurements #1523 is oriented to a specific application. There are other situations such as reference cell calibration or determination of STC module ratings that require other options or greater flexibility.

Describe the solution you'd like This feature would add a more general function or functions to address these needs and also permit exploration of alternative methods in cases where there is lack of clarity or consensus.

Additional context Preliminary discussions about additional options and desired flexibility are found under #1524