Send telemetry immediately when measured value changes significantly

[lptr]

When some measured telemetry changes suddenly in a significant way, send an update immediately. This could help provide a much smoother UX for when the rate of flow changes from 0 to X when the valve is opened.

Events to trigger immediate telemetry sending:

• value goes from 0-like to non-0-like or back
• value more than doubles or halves