Range datepicker

[annistone]

Hello! I made a date picker inspired be https://longbill.github.io/jquery-date-range-picker/. It looks like this: It's my first elm pull request, so I am not sure that I did it right way. I made API compatible with old RangePicker, but moved mine to the new module. So there new RangeDatePicker.elm and elm-range-datepicker.css and example range2( I'm not sure how to name it because range example already exists).
Related issue: https://github.com/elm-community/elm-datepicker/issues/51

[bbqbaron]

Wow! I'm super impressed. I'm reluctant to merge this for one reason (that has nothing to do with the great work you did): the repo would take on responsibility for maintaining a lot more functionality that it has now--so, we'd have to ensure that the range picker is not broken by changes, etc etc. Since the Elm community is not planning to host a datepicker at all in 0.19, it seems like a large expansion.

But! I don't want your work to be wasted. Here are some options I can think of; what are your feelings? What if this were a separate Elm package that uses Datepicker?

[rlopzc]

@annistone awesome work! I've forked and merged your PR to use it in a project! Thanks for this https://github.com/regalii/elm-datepicker