1. Restore the capability to run and debug without a subprocess.

1. Restore the capability to run and debug without a subprocess.
2. Add an indicator to the shell startup notice when running w/o
   subprocess.
3. Improve exception reporting when running a command or script from the
   command line.
4. Clarify the fact that breakpoints set or cleared after a file is
   saved will revert to the saved state if the file is closed without
   re-saving.
5. If user tries to exit or restart when user code is running, interrupt
   the user code.  This helps to eliminate occasional hanging
   subprocesses on Windows (except for Freddy :).

M NEWS.txt
M PyShell.py
M ScriptBinding.py