Consider OTRv4 modes
Created by: claucece
As we are currently implementing the revision number 2 of the OTRv4 specification, we need to include a consistent way of using the OTRv4 modes. Note that we are currently implemeting OTRv3-compatible mode.
Please, refer to the "OTRv4 Modes" section of the OTRv4 spec.
- Check how the library will allow the different modes.
- Check how a client can know about them.
- Check how a client can talk between them.