Move ConsoleExtensions.WriteCompoundStackTrace to the one place it is ever called from.
Listener.CaseSkipped(...) accepts a SkipResult containing the Case and optional Reason text, instead of simply the Case.
Added test coverage for skipped test conventions with and without optional reason text providers.
Separate test coverage for the two overloads of CaseBehaviorBuilder.Skip(...).  Rephrased CaseBehaviorBuilder's treatment of the default SkipReasonProvider for readability.
Improves naming of self-tests.