This reduces the complexity of the reducer, as well as how frequently it's run. The VM will emit a targets update after a step if any target info has changed.

/ht @paulkaplan

Use the de/serialization features of the VM to allow downloading and loading project JSON

It doesn't help anything. Doing a deep compare is unnecessary because the underlying components will do the necessary comparison themselves. Simply seeing if the sprite list has changed at all is enough.

Otherwise it's very annoying to get access to the storage engine to load asset data.

Otherwise the VM can't JSON.load it.

If the app is loading with an initial project id, don't try to load the default project. Previously, this data would load on top of the project being loaded.

Does not fix the issue of blocks not loading in the blocks pane, which appears to be separate.

With jscodeshift thank God

* Set editing target when double clicking on sprite in stage

* rename double clicker handler and add comment

* Fix costume loading in sprite info pane

Requires LLK/scratch-vm#517

* Fix costume loading in costumes tab

Requires LLK/scratch-vm#517