External link to the Google map site.

This is probably not the correct way to do this but it works.

Open up simple-google-maps-short-code.php, search for </script> on line 63.
Add the following after that line:
<br /><a href="http://maps.google.com/maps?q=<?php echo esc_attr( $address ); ?>" target="_blank"><input type="button" value="Get Directions"></a>.
Use the .pw_button class to position your button if needed.

Pippin may want to update the plugin to correct any of my code that may not be technically correct.

Thank you again for your great work Pippin!