CCAR: solve some problems during shutdown
- singletons are deleted at exit (atexit function is called at the beginning of programs)
but order is important. Trace singleton must be destroyed last because MESSAGE
and others are called in destructor of other singletons.
So I have enforced local trace initialization in ATEXIT_ class from Utils directory
- Improve Registry shutdown (called _remove_ref to delete RegistryService object)
- add a delay between shutdown servers and kill omninames in shutdownSalome.py
