* Mark transpiled JSX elements as pure
* Avoid duble annotation
* Add "pure" option to the React preset
* Fix generator indentation
* Update tests
* Add tests for the "pure" option
* Update windows fixtures
* add transform-class-properties to stage 3, set spec mode to default
* update readme with examples; use `buildUndefinedNode()`; change behavior to always define both static and nonstatic class properties regardless of spec/loose mode; update tests
* Remove whitespace generation and rely on default printing
Changes to printing:
* Add newline after last empty SwitchCase
* Add newlines around block comments if they are non-flow comments or contain newlines
* Fix a few more fixtures