Don't let disposition at end of dialogue be below 0 (Fixes #3584)

apps/openmw/mwdialogue/dialoguemanagerimp.cpp

@@ -448,6 +448,12 @@ namespace MWDialogue
     {
         MWBase::Environment::get().getWindowManager()->removeGuiMode(MWGui::GM_Dialogue);
 
+        // Clamp permanent disposition change so that final disposition doesn't go below 0 (could happen with intimidate)
+        
+        float curDisp = static_cast<float>(MWBase::Environment::get().getMechanicsManager()->getDerivedDisposition(mActor, false));
+        if (curDisp + mPermanentDispositionChange < 0)
+            mPermanentDispositionChange = -curDisp;
+
         // Apply disposition change to NPC's base disposition
         if (mActor.getClass().isNpc())
         {