Allows consumers of gui (desktop, android, etc) to rebuild gui with a relative path for static assets. Default is an absolute path as that is what is required for www.

Update scratch-render to the latest version 

Update scratch-paint to the latest version 

Remove focus selecting in slider prompt

It is not reliably selecting the input and is making it hard to type into.

Update scratch-vm to the latest version 

chore(package): update scratch-render to version 0.1.0-prerelease.201…

Slider range change with decimal value support

Make the stage color picker work with touch.

A few modifications were made while making this test:
- Change the "defaultMin/Max" to just be called "min/max", and pass the state through to make the inputs a controlled component. It is best to make form elements controlled since it makes it more clear how data flows.
- Force the passed in data to always be of type `number`, and transform it in the constructor to always be of type `string`, and change the onOk to transform it back to a number. With inputs, it is best to be very explicit about data types, and make it clear where you are using strings and where you are using numbers.
- Do not reset the state to `0` when the field is blank, that makes typing into it very hard (only applies after making it a controlled field)
- Use consistent booleans. Since the VM uses `isDiscrete`, change it so we do not use any opposite flags (like `decimal`) for clarity.

Writing tests for this really helped me understand the behavior. If you read through the test descriptions and see anything you did not intend, let me know.

fix(UI): fix cursor property when hovering account nav items

fix(css): fix css value has mixed support warning

Update scratch-svg-renderer to the latest version 

Run pify package through babel loader.

chore(package): update scratch-vm to version 0.2.0-prerelease.2019030…

chore(package): update scratch-blocks to version 0.1.0-prerelease.155…

Closes #4626

chore(package): update scratch-vm to version 0.2.0-prerelease.20190304203619

Closes #4622

Add Boost extension "coming soon" tile

Update scratch link icon

Closes #4609

Closes #4558