Feature Request: User Setting: Force UIv4

Now that UIv4 is looking pretty good (there, I said it!), we want new users to ONLY have that experience.  This will:

• Ensure they're getting the better experience
• Remove the need to train them twice
• Avoid confusion cause by their UI not looking like:
  • ours on screen shares
  • documentation

At the USER level, therefore, please add a new option:

1. Allow either (default)
2. Force UIv4