* [d3-contour] [Chore] Add contributor
* [d3-geo] Chore and Preparation for strictNullChecks
* [Chore] Change geoJSON to module import
* [Chore] Update return type signatures for `geoPath(...)` invocation. For the time being split the signatures for rendering to svg vs canvas. The return type for rendering is changed to `string | null`. This change corresponds to the comitted PR 98 in the d3-geo repo. The behavior and the definitions are now harmonized with d3-shape generators like `arc(...)`.
* [d3-contour] Update test to reflect `geoPath` change.