Fritz tiled vectors

Leaflet vectors tekenen:
- [x] Tiled Leaflet laag die data ophaalt
- [x] laag tekent geojson en refresht wanneer nodig
- [x] callback van data stored spull in vector service
- [x] on click snap to centroid
- [x] draw radius based on amount of overlaps
- [x] only draw one circle per coordinate set.
WTF hebben we aan zo enen comment?