* Added a cancel button returning 1 if clicked
* Renamed the Close button to Ok, still returning 0 if clicked
* Added --ok-label=TEXT option to change the Ok button label
* Added --cancel-label=TEXT option to change the Cancel button label
* Added --checkbox=TEXT option to show an "I Agree and accept the terms" checkbox
If --checkbox is enabled, the Ok button will be disabled if the checkbox isn't checked.