if user gets type answer wrong, show correct answer

Users could previously do that by putting the field in the template, but as so
many users think they've hit a bug when they've actually selected the wrong
field to compare to, we force the display of the field content instead.

aqt/reviewer.py

@@ -375,6 +375,8 @@ Please run Tools>Maintenance>Empty Cards""")
         given = self.typedAnswer
         # compare with typed answer
         res = self.correct(cor, given)
+        if cor != given:
+            res += "<br>" + _("Correct answer was:") + "<br>" + cor
         # and update the type answer area
         return re.sub(self.typeAnsPat, """
 <span style="font-family: '%s'; font-size: %spx">%s</span>""" %