Move to elm-community

[j-maas]

Coinciding with a rework of the code and a merge with https://github.com/wittjosiah/elm-ordered-dict, renaming the package to follow the guidelines would be the most elegant path for dealing with breaking changes.

At the same time, moving to elm-community might simplify future maintenance.

[j-maas]

A transfer to elm-community was requested: elm-community/guidelines#99

[j-maas]

I will keep the repo here, at least for now.