Except. handl'g, fn name modifications, etc

1. Added exception handling to DDE server create block. This will
prevent PyZDDE from error out when multiple applications try to create
DDE server...
2. Modified helper function names within PyZDDE to start with an
underscore.
3. Changed function ipCaptureWindow, ipCaptureWindow2 and
ipGetTextWindow to ipzCaptureWindow, ipzCaptureWindow2 and
ipzGetTextWindow respectively. This will enable easy distinction of the
different types of functions.
4. Updated License text to include Southern Methodist University