• Added check for $^S to the DIE handler inside the _worker_main method
  
• Added setpgrp(0,0) to MCE::Signal's BEGIN block
  
• MCE::Signal points to a _mce_sess_dir hash in the event of a signal,
  will remove the sess_dir(s) as well. This is needed when tmp_dir is
  specified during instantiation and pointing to another location than
  MCE::Signal::tmp_dir.