Dynamic filter minAccuracy

[pchampio]

I'll love to change the config.filter.minAccuracy value depending on the zoom level.

My use case is the following:

• When looking at the map of a car trip (100km), the zoom level is low, I don't care if the accuracy is <100m.
• When looking at the map of a small hike (10km), the zoom level is high, I want a good accuracy <10m.

The best implementation for me would be to have minAccuracy compatible with a mapping between the zoom level and a requested accuracy value.