Replace use of old Google Charts API

[grahamu]

Weather graphs are no longer produced because the old chart.googleapis.com link no longer works. Apparently one needs to load some code and invoke the chart creation.

Try this and see a 404:
https://chart.googleapis.com/chart?cht=lxy&chs=600x240&chd=e:&chco=0000FF,87CEEB,BEBEBE&chxt=y,r,x&chxl=2:%7c%7c2a%7c4a%7c6a%7c8a%7c10a%7c12%7c2p%7c4p%7c6p%7c8p%7c10p%7c&chxr=0,200,-200%7c1,200,-200&chxs=0,909090%7c1,909090%7c2,B0B0B0&chls=4%7c2%7c2)%20no-repeat%20top

Google Charts (new) Quickstart:
https://developers-dot-devsite-v2-prod.appspot.com/chart/interactive/docs/quick_start