Graphs are able to access .tab pages, but there is no easy/good way to get geometries. Additionally, Vega2 only allows `TopoJSON`, which it internally converts to `GeoJSON` for processing (TopoJSON has ~4x space saving for transmission). The problem is, we already use the less efficient GeoJSON, which means that graphs are not able to consume them directly.
I see several solutions:
* Encode geojson to topojson in PHP via mwapi.
** **PROs**: direct db access, allows to eventually store data as topojson
** **CONs**: more like a blocker - there is no PHP topojson encoder, only decoder
* Do all TopoJSON processing in Kartotherian
** **PROs**: established JS libraries
** **CONs**: Kartotherian becomes a proxy, converting mwapi response into a TopoJSON
* Patch Vega to allow direct GeoJSON consumption
** **PROs**: Client-side only code, consist backend for all features
** **CONs**: We continue wasting 4x bandwidth for the map data transmission, possible Vega fork