Core/SmartAI: Allow SMART_ACTION_FOLLOW to take 0 values for dist and angle - will set them to their "default" following values.

src/server/game/AI/SmartScripts/SmartAI.cpp

@@ -796,8 +796,8 @@ void SmartAI::SetFollow(Unit* target, float dist, float angle, uint32 credit, ui
         return;
     SetRun(mRun);
     mFollowGuid = target->GetGUID();
-    mFollowDist = dist;
-    mFollowAngle = angle;
+    mFollowDist = dist ? dist : PET_FOLLOW_DIST;
+    mFollowAngle = angle ? angle : me->GetFollowAngle();
     mFollowArrivedTimer = 1000;
     mFollowCredit = credit;
     mFollowArrivedEntry = end;