Resolve native references later to avoid import order problems?

Moved here from #11 via @rogeriochaves

> It would be much better if we could not depend on loading order, with a solution like this: https://github.com/elm-community/webgl/pull/14/files
>
> But idk if this will work for elm-testable, what do you think? Any ideas?

Start by reading the context moved from issue #11 and compare the proposed approach in elm-community/webgl pull request 14. Check whether resolving native references later is compatible with elm-testable and how it would remove import-order dependence. Done means a decided, documented approach with the compatibility concerns resolved.

Written by the indexing model from the issue text.