Feature Request: make wagyu container neutral

mapbox::geometry class templates are container neutral, that is, I can set container type as second template argument.

On the other hand, all geometry types in wagyu uses default argument which is std::vector.
It would be nice for wagyu to support arbitary container just like that mapbox::geometry does.

Start by locating wagyu's geometry type templates and comparing their default std::vector container argument with the container parameter used by mapbox::geometry. Trace the geometry operations that construct or pass these types, then verify that arbitrary containers work consistently across union, intersection, difference, and xor operations.

Written by the indexing model from the issue text.