The project loader that is exported with GUI just expects to be passed projectId as a prop, and it manages loading project data.

The part of the project loader that watches for URL hash changes for the playground is a new HOC that is only used in the various playground examples.

Add setAppElement to GUI.

Fixes #1853 

Add random backdrop menu option

Fixes #1853

Update scratch-render to the latest version 

Replace buffer-loader with arraybuffer-loader

Replace babel-preset-es2015 with babel-preset-env

Optimize the logo SVG

Update to webpack 4

It was 435KB. Now it's 5KB. I used SVGOMG: https://jakearchibald.github.io/svgomg/

Add several new integration tests to the GUI

Large readout mode for monitors

Root cause is probably the flex implementation on Safari.

Sprite upload

Bump scratch-blocks version

Bring in https://github.com/LLK/scratch-blocks/pull/1464

Limit toolbox updates

Update calls to addSprite2 to use new API for adding sprites. Cleanup sprite3 representation for uploading a new sprite from an image.

Update vm with real offsetting fix