Iterator for continuos datetimes

I recently wrote this iterator on StackOverflow for generating continuos `datetime` objects: https://stackoverflow.com/a/48136062/2063361

I think it will be a great fit for Maya. Should we be adding this? If so, let me know, I've a pull request ready ;)

Review the linked Stack Overflow iterator and Maya's existing datetime APIs to understand the proposed behavior. Check whether the author's mentioned pull request is available, then identify the relevant tests or entry points for datetime iteration. Done means the intended API and continuous datetime behavior are covered by tests.

Written by the indexing model from the issue text.