Case constructs its own CaseExecution, rather than the other way around, as a step towards making Case the behavior context object instead of CaseExecution.
Case is a BehaviorContext; CaseExecution is no longer a BehaviorContext.
ClassExecution owns the list of Cases to be run for the test class, not just the associated CaseExecutions.
InstanceExecution owns the list of Cases to be run for the test class instance, not just the associated CaseExecutions.
Simplify LifecycleTests in light of recent changes to CaseBehavior.
FailResult and PassResult are constructed with a Case instead of the associated CaseException, making them more like SkipResult.
Phase out remaining usages of deprecated property CaseExecution.Case and remove it.
Simplify the handling of exceptions thrown during custom test case parameter generation now that each Case has-a CaseExecution of its own.
FailResult, PassResult, and SkipResult no longer expose the whole Case directly.
The deprecated CaseExecution class no longer owns the test class Instance property for a case.  Instead, Case owns the Instance property.
The deprecated CaseExecution class no longer owns the Duration property for a case.  Instead, Case owns the Duration property.
The deprecated CaseExecution class no longer owns the Output property for a case.  Instead, Case owns the Output property.
The deprecated CaseExecution class no longer owns the Result property for a case.  Instead, Case owns the Result property
Case exposes members equivalent to the remaining public members of deprecated CaseExecution, implemented by defering to the CaseExecution implemetation, so that usages of CaseExecution can be phased out.
Phase out usages of deprecated property Case.Execution.
Phase out CaseExecution now that Case handles those responsibilities.
Rename ClassExecution.TestClass property to Type, so that ClassExecution can be renamed to TestClass in the next commit.
Rename ClassExecution to TestClass.
Rename TestClass to Class for consistency with the rest of the system (conventions discover these via the Classes property, etc).
Case.Instance becomes Fixture, and references teh InstanceExecution rather than the test class instance directly.