Changed withPayloads to infer and return the same type as the passed in function, and changed payload: Any parameter to => Any to be lazy.
Fixed withPayload not working in withFixture problem.
Fixed withClue not working in withFixture problem.
Rewritten withPayload and withClue to handle Failed and Canceled separately.
Added payload to TestCanceledException.
Added more tests for withPayload and withClue.
Merge branch 'payload' of https://github.com/cheeseng/scalatest
Tweak tests to get rid of Omitted and message in Pending.