Create a function to create general skill scores

[nikosbosse]

We currently have the function pairwise_comparison() and add_pairwise_comparison(). Pairwise comparison are just one particular form of skill score, and I think it could be possible to create a function that would allow the user to create arbitrary skill scores based on their forecasts

[nickreich]

Has any progress been made on this front? I think it would be really valuable to have this.

[seabbs]

Yes agree and I think no not yet - this is what we would need as well for some of the PAR work I think