Mute warning from groovy when running on java 6.
Moved sanitization of stack trace from BuildExceptionReporter to ExceptionAnalyser, so that exception reporting works on Java 5.
Added some validation early during startup to ensure that we're running on Java 6 or later.
Changed DaemonStateCoordinator so that it does not throw an exception when stop is requested before idle timeout is reached.
Tightened up validation of build error output.