Add operations for Extent type

[henrik-wolf]

Would it be possible to add the appropriate GeoInterface methods (intersects, intersection, contains, union...) for the Extents.Extent type to this package?
It feels a bit strange to have GeoInterface everywhere, except when working with extents, where you have to qualify the operations.

Ideally, this should go into Extents itself, but that does not seem possible. (and would this be considered type piracy? I am not sure, since GeoInterface owns the methods...)

[evetion]

Yeah, we should add those methods here. Good catch.

[rafaqz]

We should fill out all these methods in Extents.jl for just comparing extents with each other, which we partly have already and I'm extending in rafaqz/Extents.jl#13

Then we can use those to build GeoInterface methods here on geometries with extents.

Extents.jl cant add GeoInterface methods because the dependency is the other way around

[evetion]

Nice, this is exactly what I wanted to make an issue about, missing methods (within, etc) in Extents, that I can cover with GeoInterface. Will have a draft PR up soon for related work here.