AQI color display

Adopted guidelines for color display of AQI published 2018 by the EPA in AQI Technical Assistance Document.

AQI fixes

This version puts AQI under the optionalAccessories condtional for backward compatibly with 3.x db schema, and applies the standard yellow/orange/red/etc colors to the table-cell containing AQI when it's above 50.

AQI added

Davis Instruments released a new product in Aug 2020, the AirLink 7210 air-quality monitor. This version supports graphs generated by the plugin from John Kline's repo, https://github.com/chaunceygardiner/weewx-airlink.

Forecast module disabled

Forecast hasn't worked since Sep 2018 when IBM withdrew the forecast API. Also, the python code this depends on isn't ported from python2 to python3.

First working version

Has these capabilities beyond the Standard skin:

• Includes a Forecast page with the same look & feel
• Provides a banner image (customize in weewx.css), and improved clarity of the charts
• Adds yesterday/today columns
• Eliminates some redundancy of template contents