When asked to load an extension, the Extension Manager starts up a new
Worker. That worker runs the message dispatch system as well as an
instance of the new `ExtensionWorker` class, which will load the desired
extension and register it with the extension system.
Extensions, placed in `./src/extensions/*.js`, are now processed by
Webpack as separate entry points and packed into an `extensions`
subdirectory in the output.
Still to do: query an extension's information, including the blocks it
provides, and register that information with the VM, GUI, etc.
The previous configuration mixed Webpack output with static content in
order to create the playground. This change moves that static content
from `/playground/` into `/src/playground/` and adds a Webpack rule to
copy it into the playground as part of the build.
On the surface this might seem unnecessary, but it provides at least two
benefits:
- It's no longer possible to accidentally load stale build output
through `webpack-dev-server` in the event of a misconfiguration. This
was very easy in the previous configuration, and might in fact be the
only way that `webpack-dev-server` ever worked for this repository.
- It's simpler to ensure that various rules apply to the hand-authored
content and not build outputs. This includes lint rules, `.gitignore`,
IDE symbol search paths, etc.
* `module.loaders` -> `module.rules`
* loaders need `-loader` suffix
* `json-loader` is enabled by default
* `UglifyJsPlugin`'s `compress.warning` setting is false by default
* Move Node output: /dist.js => /dist/node/scratch-vm.js
* Move web output: /vm{.js,.min.js} => /dist/web/scratch-vm{.js,.min.js}
* Update build output references in package.json and the playground's index.html
* Move the VirtualMachine class out of index.js into its own file, referenced by index.js. The VirtualMachine class is otherwise unchanged.
* Add .gitattributes rules for new file types which were added to this repository without specifying their text/binary attributes
* Turn on source maps in webpack and add corresponding .gitignore rule
