Some minor edits to testing spec, reordered some later stories.
Some tweaks to SetupBuild task type.
Added package cycle checks to buildSetup project.
Use the TestExecutionFailure fixture to look for certain build error messages, rather than scraping the output.
Changed InProcessGradleExecutor to run the builds with --stacktrace by default (as the forking executor does).
Removed unused class.
Don't document internal property.
Some rough performance notes.