Feature: Editor Framework

This adds the beginnings of an editor framework. It adds:

* Vibe-d as a dependency
* Custom WebSocket server
* Framework for sending and receiving messages
* The ability to get a callback on a response
* The ability to respond to a received message

There's still lots to do for the tools framework, including a more useful front end framework, and more engine side hooks for actually changing things. That said, this will allow game teams to start setting up actual events.