Prevent previous tutorial images from hanging around on next/prev

Add VM init callback

Revert "Revert "Merge pull request #4790 from LLK/e16n""

Revert "Merge pull request #4790 from LLK/e16n"

This reverts commit c061f2e2, reversing
changes made to 6e007b1e.

skip example change categories test

Make Updates to Tutorials Library

Update l10n

Updates to sprite and costume libraries

Supporting GUI changes for extensionification

Comments slightly tweaked from kchadha's suggestions

Co-Authored-By: Karishma Chadha <kchadha@media.mit.edu>

Update l10n to the latest version

Update scratch-vm

Greenkeeper didn't do this for me... not sure why.

Show libraries before loading their content

Use a "title card" instead of video if using Scratch Desktop

Because the video steps get replaced by an image step if offline, we should not show items that would result in having no content

Update scratch-render