Autosuggest new context

[raineorshine]

When adding a thought to a context (newThought in context view), autosuggest existing contexts.

• Show suggestions as subthoughts underneath typed thought, with helper text “Suggestions”
  • Helper text is small text that appears underneath a context, e.g. the Context View has helped text “Contexts:”
• Render suggestions using ContextBreadcrumbs with a custom click handler.
• Reuse Search matching
  • Match any part of a context e.g. if you type "Todo" then it should suggest /Work/Todo, /Home/Todo, /A/Todo/B
  • Match partial: /Work/MyTodo
• Tapping anywhere on the suggestion will replace the partially entered context with the selected context and correctly add the thought to it.

[raineorshine]

Hold until context view is working more reliably.