Core: Codestyle clean-up

"pl"->"player"

 Note: codestyle methods needs maintained, Player* player.
still to do properly clean-up chat.cpp.

src/server/game/Entities/Creature/Creature.h

@@ -607,7 +607,7 @@ class Creature : public Unit, public GridObject<Creature>, public MapCreature
         CreatureSpellCooldowns m_CreatureCategoryCooldowns;
 
         bool canStartAttack(Unit const* u, bool force) const;
-        float GetAttackDistance(Unit const* pl) const;
+        float GetAttackDistance(Unit const* player) const;
 
         void SendAIReaction(AiReaction reactionType);