Move TestAssembly and Convention to the root namespace because they are used by consumers during typical usage.
Move CaseBehavior, InstanceBehavior, and ClassBehavior to the root namespace because they are used by consumers during typical usage.
Move Runner and ClassRunner to the Fixie.Execution namespace.
Move ExecutionEnvironment and ExecutionPlan to the Fixie.Execution namespace.
Move AssertionLibraryFilter to the Fixie.ExecutionNamespace.
Move convention DSL helper classes to the Fixie.Conventions namespace.
Rename ConfigModel to Configuration.
Move Listener, PassResult, FailResult, and SkipResult to the Fixie.Execution namespace.
Move GenericArgumentResolver to the Fixie.Discovery namespace.
Move ObjectExtensions to the Fixie.Discovery namespace.
Move Shuffle<T>(...) to the one place it is called.
Move Fixie.Behaviors classes to the Fixie.Execution namespace.