Install react packages as dev dependencies

[eatyourgreens]

Move react, react-dom and prop-types to dev dependencies.

[eatyourgreens]

I think this will stop Markdownz from installing React 15 when the parent project is using React 16.

[srallen]

This is working with the react 16 branch.

Similar to my comment on zooniverse/Seven-TenClient#react-dependency, using peer dependency might be more appropriate.

[eatyourgreens]

Should zooniverse/modal-form use peer dependencies too? We've not declared them before.

[srallen]

I think they might be a better way to go for long term maintenance. I had the same thought as you that they were deprecated, but I learned from the grommet team that they are not, just the auto-install part was deprecated.

[eatyourgreens]

Would something like

peerDependencies: {
 "react": ">= 15.6"
}

include all versions since 15.6, including 16?

[srallen]

Hm, I'm not sure if that would include 16. The grommet source uses an || to specify the React 15 and 16 ranges they support: https://github.com/grommet/grommet/blob/master/package.json#L27

[eatyourgreens]

That's going to be painful when the major version changes again. ☹️

[eatyourgreens]

Let's see if the latest commit throws a warning with React 16.

[eatyourgreens]

Published as 7.6.0.