Switch Preact to React

[pascalw]

Switch the generated project from Preact to React.

• Preact is unfortunately not keeping up with React, so we're missing out on some newer features like fragments, portals, Lazy, Suspense etc. (Some of these features can be achieved in Preact, with 3rd party plugins).
• Preact can be a pain when used with 3rd party plugins. A lot of React plugins are not compatible with Preact.
• React is now MIT licensed.
• React is still quite a bit larger than Preact. For mobile apps this is a drawback, though React 16 is already lighter weight than React 15.