ONE: NATstyle: automatic execution of 'Clear NATstyle Violations'

When a Natural source is modified after a 'Check Code with NATstyle' has been executed the former violation markers are probably not valid any more. The user has to start 'Clear NATstyle Violations' manually to make them disappear.

Even if you start a new run of 'Check Code with NATstyle'

- you have to clear the existing violation markers before

- or at least Save the source before executing the check

Otherwise the old markers remain.

It would be more comfortabe if the violation markers were cleared automatically when the Natural source is being modified / or Saved / or Checked anew (maybe selectable by a new option in the Preferences).