Added debug logging for master state transitions
added more tests for unsol/read collisions
Fixed a bug where slave would cache defferred requests even after a layer close
Fixed a conformance issue with unsolicited

When the outstation receives a READ request while waiting for an
unsolicited confirm, it should abort any retries.
Merge branch '1.1.x' of https://github.com/automatakllc/dnp3 into 1.1.x