Support vector data in any projection

[kb173]

At the moment, vector data has to be in webmercator for consistent coordinates. It would be ideal to convert coordinates on-the-fly (assuming the position passed to the function is always in webmercator meters) so that we're independent of the original projection of the data.

We would need to set the coordinate system / projection of the circle we construct for intersection, and to read and set it on the dataset at the given path in the VectorExtractor.

[chrisgraf]

As recently discussed for geodot we can assume a consistent projection for the input geodata. We currently will require MGI Austria Lambert