Vehicle marker scaling

[roata]

Our vehicle markers are always of the same size, regardless of the zoom level.

High-level overview:

Detailed view:

Markers should be smaller when we're looking at a high-level view, and bigger when we zoom in. At some point, when hundreds of vehicles will be tracked - the map will turn into a "sea of red", which is not informative in any way.

[unrevised6419]

Note:

• https://github.com/Leaflet/Leaflet.markercluster

[roata]

Yeah, I guess that would be even better, though I am not sure how it would look like in a dynamic setting. If we're looking at buildings, that's alright, but we're dealing with moving targets, I wonder how the clusters will behave in this case :-)