iso-fns: date-fns that only work on ISO strings

[lax4mike]

Javascript's Date sucks. TC39 even thinks so and they're making a replacement.

All of date-fns work on Javascript's Date object but maybe they don't have to. I'm building a calendar app and storing my dates as ISO strings (because Javascript's Date sucks). Every operation that I do I have to parseISO, do the thing, then formatISO. What if we cut out the Date middle man and just worked on iso strings instead? Is Date doing a bunch of heavy lifting for date-fns?