Average multiple sensors?

[obra]

Related to #67 - Since we don't start off having even 2 minutes of data, I've been thinking about whether we might want to consider finding the 3 nearest sensors (ideally in different directions) and averaging them.

[skalnik]

Not a bad idea! I'm hesitant to add things we can't link to as verification to avoid confusion, but maybe if we add some kinda settings and let folks toggle this on/off?

Also, we'd definitely want some limit on distance. In the Bay Area, due to our unfortunate history with wildfire smoke, the PurpleAir sensor network is rather dense. However, other places may not share that same density and it may not be as helpful to average together a sensor right next to someone and one that's very far away.