[3.0] Put `params`, `location`, and `route` on `context.router`

[ryanflorence]

These are all really useful deep in the tree, especially when building links. Instead of asking folks to take them from their route components and put them on context there, we should probably just do it.

Thoughts?

[taion]

We want to be careful about what we mean by location – the location that the router sees is not the location that history sees, in the case of an async transition.

Otherwise it probably makes sense to put these on the context.

[timdorr]

That location is the one after we have resolved the async stuff, correct? That would seem to be safer than history's, since it doesn't ever get out of sync with what the router is attempting to display. (re: the react-router-redux 4.0 changes).

[ryanflorence]

"the location we used to render", whichever one RouterContext got from Router.

[taion]

Makes sense to me. @timdorr, you'll want to add a caveat in React Router Redux that this won't match whatever location ends up in the Redux store (err, does React Router Redux still have an option to do that?).

[ryanflorence]

Looking at the code, this will be a lot simpler after 3.0. Not that it's hard, it's just that where we provide context is pretty messy from all the deprecations. Maybe we should just ship this w/ 3.0 when we can clean all that stuff up.

May 9th is when we can release 3.0, so maybe let's figure out everything we want for the next minor release, release it, and then make a 3.0 branch to start removing deprecations and such (use a branch so that we can do some bug fixe releases from master if we need to).

[taion]

What do we think of putting router on the props for route components as well, then?

[timdorr]

Since we're doing that via withRouter, it makes sense to get it for "free" with a route component.