Scoped themes to apply only to the editor (#editor-holder)
Removed theme class from being applied to the document
Removed all code to handle multi theme selection
Adding change to process theme in the extension package as an object rather than just a string
Update metadata for built in themes and look for the `dark` flag in the right place.
Merge branch 'master' into MiguelCastillo-themes-8420
Theme test fixes
Minor jsdoc tweak