Support @material-ui/core 4.x

[dantman]

Right now this library only includes MUI 1.x-3.x in the peerDeps.

Given how thin a wrapper this library is, it should probably just use >= 1.0.0 instead.

[OnkelTem]

I don't understand can we use it with @material-ui/core 4.x?

[TylerRick]

It's not really updated for 4.x yet. Maybe some components work but I ran into some issues when I tried using it with 4.x.

I've switched to this fork: https://github.com/rainerschuster/final-form-material-ui, since this upstream project is no longer actively maintained.

[lookfirst]

Hey all... I was frustrated by the lack of maintenance here and surprised npm reports 7.5k downloads per month of this. So, I've done my own version...

Code: https://github.com/lookfirst/mui-rff
Demo: https://lookfirst.github.io/mui-rff/

All modern, typescript and jest tested.

There is 1000 variations to what people may want, so submit PR's if I'm not hitting on your exact wish.