Upgrade to the latest version of flowtype

[alexreardon]

Details:
https://medium.com/flow-type/even-better-support-for-react-in-flow-25b0a3485627

/cc @thejameskyle how would this change play with your prop type generator?

[jamiebuilds]

I need to rework it to lookup Props from the type parameter instead of from the class property.

[alexreardon]

I am thinking of dropping the generating of react prop types as they are not used for any doc generation. We could always add it in later

[alexreardon]

https://flow.org/en/docs/react/

[alexreardon]

I tried to upgrade, but sadly I am unable to until eslint-plugin-react is fixed: jsx-eslint/eslint-plugin-react#1376

[jamiebuilds]

jsx-eslint/eslint-plugin-react#1376 (comment)

[alexreardon]

I think we should be good to start on this one now

[alexreardon]

I tried to upgrade today but the eslint plugin is still yet to be fixed. No harm in waiting for now

[alexreardon]

Closed by #181