Implement convex hull for geometries other than Polygon

[JosiahParry]

Using geos, the convex hull can be provided for all geometry types. An oddity, though, that I've noticed is that it does not always return a polygon.

For example:

• Point -> Point
• Line -> Line
• LineString (3+ coords) -> Polygon
• MultiPoint (2 coords) -> Line
• MultiPoint (3+ coords) -> Polygon (could just as well be a triangle)

[JosiahParry]

Closing! I misunderstood the docs! It works as anticipated :)

Though perhaps the docs can be updated?

"Returns the convex hull of a Polygon."

Could be "returns the convex hull of a geometry." The phrasing makes it seem like it is only implemented for polygons.

https://docs.rs/geo/latest/geo/algorithm/convex_hull/trait.ConvexHull.html