Prevent scaffolds from revealing correct answers when feedback is not…

… permitted (really)

In openwebwork#986 I believed that this was set.  But either something has changed
since then, or I didn't have it right at that point.

In that pull request I claimed that when an answer preview occurs,
scaffolds will open but not receive the green color if all answers
within are correct.  In particular, if a preview occurs it should not
reveal that answers are correct.  Unfortunately, it still is.

This fixes that by only giving the correct colors when attempt results
are allowed.

macros/core/scaffold.pl

@@ -593,7 +593,8 @@ sub add_container {
 					'div',
 					class => 'accordion-header'
 						. (
-							$iscorrect && ($main::envir{showFeedback} || $main::envir{forceShowAttemptResults})
+							$iscorrect && ($main::envir{showFeedback}
+								&& ($main::envir{showAttemptResults} || $main::envir{forceShowAttemptResults}))
 							? ' iscorrect'
 							: ' iswrong'
 						)