Split forecast/all and pvlive/all API calls into historic and future data, in order to only automatically re-request the new forecasts from now, and not the static historic data, which doesn't change (but otherwise still gets redownloaded each time).
Fixes #418
How Has This Been Tested?
[x] Unit tests added for split functions;
[x] Vercel preview branch
If your changes affect data processing, have you plotted any changes? i.e. have you done a quick sanity check?
Pull Request
Description
Fixes #418
How Has This Been Tested?
If your changes affect data processing, have you plotted any changes? i.e. have you done a quick sanity check?
Checklist: