Frontend: Output graphs: Heat Load & Scatter

[thadk]

Rules Engine issue #17 , PR #39:

Two points for straight lines

6 pairs of numbers

scatter graph need a bit more:

• embed the data for the 90 plus existing homes.
• home size and heat-loss coefficient.
• One data pair for the current home (from the rules engine)
• two data pairs for the trendline.

[thadk]

Closed by #103 though they're not fully hooked into the data yet