Migrate to React

[svenefftinge]

Any usages of phosphor's virtual dom should be migrated to React.
See phosphorjs/phosphor#302 (comment)

[lukehutch]

(Copying comment from phosphorjs/phosphor#302):

Why not use Inferno instead? Its it is smaller and much faster than React, and in particular its virtual DOM diff implementation is much faster than React's.

https://github.com/infernojs/inferno

[svenefftinge]

It is less mainstream so it would raise more questions and mean a steeper learning curve for people looking into adopting and contributing.