Save on close settings window

[CharlesTyrrell]

Easy to open the settings window, and then close without saving, but not obvious when this has happened.

[AnthonyvW]

Will implement this as a prompt on closing Forge. Will possibly add a notification in the corner if it's not saved.

[AnthonyvW]

This is being added as part of the GUI rewrite

[AnthonyvW]

This has been added in the GUI rewrite. It now prompts you if you want to save when closing the menu.