Flatten everything

[gaearon]

Makes so that we're at most one level deep (excluding src) into each package.
Added new events pseudo-package that technically works like shared and was extracted from it.

  |-events
  |-react
  |  |-npm
  |  |-src
  |-react-art
  |  |-npm
  |  |-src
  |-react-cs-renderer
  |  |-src
  |-react-dom
  |  |-npm
  |  |-src
  |  |  |-client
  |  |  |-events
  |  |  |-server
  |  |  |-shared
  |  |  |-test-utils
  |  |  |-unstable-native-dependencies
  |-react-native-renderer
  |  |-src
  |-react-noop-renderer
  |  |-npm
  |  |-src
  |-react-reconciler
  |  |-npm
  |  |-src
  |-react-rt-renderer
  |  |-src
  |-react-test-renderer
  |  |-npm
  |  |-src
  |-shared

This makes #11303 an easier pill to swallow.

[sebmarkbage]

Hehe. Flatlandia. Classic Dan.

[jquense]

the git history seems to be gone :( https://github.com/facebook/react/commits/master/packages/react-dom/src/events/ChangeEventPlugin.js