Real Time Collaboration

[hbcarlos]

This PR follows #89

TODO:

• Update dependencies
• Create a new DocumentModel
• Create a new xml ISharedModel by extending from YDocument
• Observe shared model in DrawIOWidget
• Create types for events (docs)
• Parse events

Screencast of the final result

drawio.mp4

NOTE: As you can see on the screencast, the first time you do an action after opening the file, the view does a weird movement.