develop
Integration of all external packages into MassTransit, split out into Abstractions, Middleware, and the core MassTransit assembly.
Fix summaries of overloads referring to message type while no messageType parameter is available
AddSqlMessageScheduler() method created so that scheduled messages can be canceled
Adding nullability to abstractions, and fixing warnings
Updated the Transactional Outbox to support delayed/scheduled messages
Quartz ScheduleId/ScheduleGroup added to headers