EventDeserializer.Deserialize became enumerable

- In order to cater for upconversion needs the deserializer needs to be
able to turn a resolved event into 0, 1 or more events.
Parked some ideas in the backlog
Enhanced coverage

- When NUnit does not do what you expect
Meet AggregateBuilder

- Added a mutable builder for aggregates
- Sprinkled some of the Visual Studio Code Analysis suppression
attributes (WIP)
Taking pointers from VSCA
Oops

Forgot a file
Broken windows

- Fixed broken tests
- Fixed compilation errors (multi-solution stuff not wukkin)
Goodbye Apply, Hello ApplyChange

Just a breaking rename that brings it more in line with the other
methods
Fighting with the invisible man ...