Version 0.2.0 scope

[lukebarnard1]

A list of features that are required for a second release:

• [x] Room
  • [x] state events
  • [x] timeline event
    • [x] type
    • [x] previous content
    • [x] id
    • [x] redacted_because
• [x] Room member
  • [x] avatar URLs
  • [x] read receipt (Room.receipt)
• [x] Unhandled events (#5)
• [x] Update readme