Export files are now directly under the module folder,
e.g. `core/core.js`. With this, an import like `core/core`
won’t need a path mapping (e.g. via `System.paths`) any more.
This adds the `src` folder to all other import statements as well.
simplify:
- use same html file for dart and JS
- build benchmarks automatically when doing `gulp build`
- centralize configuration
modularize:
- move all build tasks into separate node.js modules under
`tools/build`.
changes:
- the `build` folder is now the `dist` folder
Closes#284
Tobias Bosch
Yegor Jbanov