1.0.0 Realtime API Review and Changes

[mmacfadden]

There has been a lot of churn and patchwork on the API over the years. Based on feedback and what we have learned, we need to smooth this out for 1.0.0. This issue serves as a master issue to track progress on this.

• [ ] Historical Model Consolidation: There is no longer a need to keep the HistoricalModel and RealTimeModel separate. The introduction of the "ObservableModel" muddies the API and the events. We should consider consolidation.
• [ ] Event constant definitions: Event constants are defined differently across classes.
• [ ] Chat 'ignoreExists`: This was somewhat of a bandaid, we should consider a joinAutoCreate method similar to the model API.
• [ ] IChatEvent vs ChatHistoryEntry: Review this. Having them separate is somewhat annoying to handle as a consumer, since I have to deal with both. Also the base class for one is an interface and an abstract class in the other.
• [ ] ReferenceChangedEvent should probably be renamed ReferenceSetEvent for consistency.
• [ ] Review strongly typed events: https://medium.com/@bterlson/strongly-typed-event-emitters-2c2345801de8