Adding a new "Preview Mode" option.

In response to a request from user IveTechMedia, I've added a feature called Preview Mode.

When the Preview Mode checkbox is checked in settings and Studio Mode is being used in OBS, the next scene and previous scene hotkeys will change the preview mode rather than the active program view. This means you can use the hotkeys to change your previews and then use a transition to update the main screen.

The feature defaults to active but can be disabled from the Scripts-->Tools options menu for the script.