Proper quitting #52

SOTI's interface says 'q' or Ctrl-C to quit.
Right now, q does nothing and Ctrl-C crashes the app.

Write a signal handler and a shutdown routine to shutdown gracefully on Ctrl-C
Call the shutdown routine when the user enters q as a command.

Steps:

1. Figure what resources need to be released on exit
2. Write routine to release them and close the app
3. Get the routine to run on Ctrl-C and 'q' command.