Support for blocking a creature from gaining experience, don't give experience when a creature is fainted.

src/Battling/Library/ExperienceLibrary.cpp

@@ -6,6 +6,10 @@ void CreatureLib::Battling::ExperienceLibrary::HandleExperienceGain(
     for (auto opponent : opponents) {
         if (opponent == nullptr)
             continue;
+        if (opponent->IsFainted())
+            continue;
+        if (!opponent->AllowedExperienceGain())
+            continue;
         auto levelDiff = faintedMon->GetLevel() - opponent->GetLevel() + 10;
         if (levelDiff <= 0)
             continue;