Use localStorage to save the state of the 'seperate weight' switch and date range

[fabiancdng]

Currently the 'seperate weight' switch for the compare chart flips back to 'off' as soon as you reload the page or update the charts.

My idea is to save the last state of this switch in the user's localStorage. So if the user enables the option, it doesn't get disabled on page reload or chart re-draw.

It would be nice to store the date range as well.

[AuxiliumCDNG]

Maybe also save the date range?
Would definitely be a handy dev feature.

[fabiancdng]

Maybe also save the date range? Would definitely be a handy dev feature.

Great idea! I'll update the issue