Helper class for determining whether a Throwable is fatal or not. User should only catch the non-fatal one,and keep rethrow the fatal one.

Fatal errors are errors like VirtualMachineError (for example, OutOfMemoryError and StackOverflowError, subclasses of VirtualMachineError), ThreadDeath, LinkageError, InterruptedException, ControlThrowable.

Note. this helper keep the same semantic with NonFatal in Scala. For example, all harmless Throwables can be caught by:

try {
  // dangerous stuff
} catch(Throwable e) {
  if (Throwables.isNonFatal(e)){
    log.error(e, "Something not that bad.");
  } else {
    throw e;
  }