OpenStreetMap embed

[ChildishGiant]

I'd love if there was an option for an OpenStreetMap embed over a Google Maps one. I might be able to take a crack at it given that leaflet.js makes things so easy. Just opening this issue to track interest/likelihood of getting merged

[JoeGermuska]

I'd review a PR for an OSM embed. The key thing we'd want to see is that it's easy for creators to specify -- but OSM map views carry lng/lat/zoom which is the key thing.

When TimelineJS was created, things like including Leaflet were not clear, but now that we have an NPM based build, it could be fairly straightforward. I'm not crazy about bloating the distribution bundle but maybe that won't be a big issue.