Ribbon control

[jpobst]

Although there is a basic Ribbon control, it is considered "not ready for usage", and won't be receiving any love until other higher priority tasks are completed.

Current status:

• Ribbon can be created
• Tabs can be created
• Simple buttons can be created

Basic ribbon features are missing like:

• [ ] Different button sizes
• [ ] Different button types (dropdowns, toggles, etc)
• [ ] Overflow
• [ ] Keyboard navigation