DialogInfoSubClient

Dialog-info+xml subscription client test program.

This dum test/sample program is a derivative of the basicClient program, however
it has been modified to subscribe to the dialog-info+xml event package.  Notifies
containing dialog-info+xml bodies are displayed in the log output, and a couple of
additional features are available for testing:
1.  Pressing 'a' toggles 'auto-answer' for incoming calls off/on.
2.  Pressing 'h' toggles the hold state on/off for any active calls.
3.  Pressing 'j' sends an INVITE with Join header to the first dialog in the dialog-info+xml events
4.  Pressing 'p' sends an INVITE with Replaces header to the first dialog in the dialog-info+xml events
