Remove feedback form

Resolve issue with costume Button 4-b

Upload a sound file

Fix issue where loading a project while in costume tab yields oops page.

Update vm to include fixes for video transparency

Update vm to include video motion fixes for other browsers

Adjust language in selectors and libraries

Add EV3 and microbit to extensions library

Fix issue with sound upload button not always working, and correctly cache sound type if given an mp3.

Update scratch-vm

Re-order motion blocks

Add File and Edit menu dropdowns

Add editor drag mode for popping sprites of stage.

There's a subtle difference in behavior between mouseup and click. Using mouseup allows you to close the menu by clicking its opener item.

whoops