qst: add showResult markup option

The new markup option allows to hide the results of the question (the explanations and points) but still allow showing points. This may be needed in courses where a student has one chance to answer the question and see the points, but not see the correct result.

timApp/plugin/qst/qst.py

@@ -140,6 +140,7 @@ class Meta:
     # TODO: Convert old QST formats to the new format in production
     json: dict[Any, Any] | None | Missing = missing
     title: str | None | Missing = missing
+    showResult: bool | None | Missing = missing
 
 
 QstBasicState = list[list[str]]
@@ -250,7 +251,14 @@ def qst_answer_jso(m: QstAnswerModel):
     show_points = (
         info.show_points if info is not None and info.show_points is not None else True
     )
-    if not show_points:
+    show_result = True
+    if isinstance(m.markup.showResult, bool) and not m.markup.showResult:
+        show_result = False
+
+    if not show_result:
+        result = False
+
+    if not show_points or not show_result:
         jsonmarkup.pop("expl", None)
         jsonmarkup.pop("points", None)
         jsonmarkup.pop("defaultPoints", None)
@@ -723,7 +731,8 @@ def qst_try_hide_points(jso):
         info, "earlier_answers", 0
     )
     show_points = info.get("show_points", True) if info is not None else True
-    if not limit_reached or not show_points:
+    show_result = markup.get("showResult", True)
+    if not show_result or not limit_reached or not show_points:
         markup.pop("points", None)
         markup.pop("expl", None)
         markup.pop("defaultPoints", None)