add imutable ids to some exam arrays to detect and log changes between two exams.

src/stores/examEditor/reorder/global.ts

@@ -59,8 +59,8 @@ const reorderWriteBlanks = (exercise: WriteBlanksExercise, startId: number): Reo
     let newIds = oldIds.map((_, index) => (startId + index).toString());
 
     let newSolutions = exercise.solutions.map((solution, index) => ({
-        id: newIds[index],
-        solution: [...solution.solution]
+        ...solution,
+        id: newIds[index]
     }));
 
     let newText = exercise.text;