Refactor Turbolinks

[marutypes]

So, I've talked about this in private with a few of you, and I have brought it up in some of the recent PRs as well. I'm just opening this issue to keep track of things and also to allow some public discussion.

I think our domain model is wrong and causes changes to take longer than they should. I'd specifically like to take Turbolinks.visit into more of an 'instantiating a visit object' direction, and away from the current strategy of having a bunch of static methods and an options object that we mutate.

I'll probably be away from this repo for a bit but I'd like to come back to this (and the other open issues) by the end of the year.