Context menu operations for ribbon layout management

[robobenklein]

• [ ] Close patch
• [ ] Close Column
• [ ] Split patch:
  • [ ] Left
  • [ ] Right
  • [ ] Up? (do people use this, is there a reason?)
  • [ ] Down
• [ ] Move column or patch: (swapping, only displayed when possible? e.g. at top/bottom/left/right edges)
  • [ ] column right/left
  • [ ] patch up/down
• [ ] New:
  • [ ] patch above/below
  • [ ] column left/right

I realize nobody ever actually used "split patch up" in all my testing... maybe just remove it? It's basically the same result as down.