Widen add-extension button to match category.

chore(package): update scratch-paint to version 0.2.0-prerelease.2018…

Do not skip safari 9 browser test because it works now

Updates to sprite, costume, and backdrop libraries

Goes along with https://github.com/LLK/scratch-blocks/pull/1646

Update vm again, bringing in variable updates

Share Local Variables from a target to another

Provide a from target id when sharing blocks to another target so that variable conflicts can be resolved.

Closes #2616

Update scratch vm to include promise reporter fixes

Update scratch-blocks to the latest version 

Fix rename variable bug

Update scratch-paint to the latest version 

Update scratch-l10n to the latest version 

Update scratch-blocks to the latest version 

Add a new "unavailable" step to the connection flow

Update libraries

Fix rename variable bug by always passing additionalVars to the scratch-blocks prompt callback. Let scratch-blocks decide whether or not to use the additional vars based on whether the variable is local or global.

Use bitmapAdapter for costume upload

Fix micro:bit extension name and description