New

• vue2: inspect getters in mutation timeline layer
• components: store last selected component for each app

Fixed

• prevent HTMLElement serialization to fail
• use clone-deep instead of fast-copy, closes #1583
• broken URL to open-in-editor docs (#1590)
• refactor: api for each backend + state editor, closes #1589
• don't auto select hidden app
• don't try to load component from unselected app
• new hidden apps were still sent to frontend
• error in watch handler
• vue2: normalize component id
• vue2: remove unnecessary root id code