[refactor] Get rid of NPC.hpp

This file was already obsoleted at the start of the refactor, but seems
to have escaped notice until now.

src/Combat.hpp

@@ -2,7 +2,6 @@
 
 #include "core/Core.hpp"
 #include "servers/CNShardServer.hpp"
-#include "NPC.hpp"
 #include "MobAI.hpp"
 
 #include "JSON.hpp"

src/NPC.hpp

@@ -1,4 +0,0 @@
-#pragma once
-
-#include "Chunking.hpp"
-#include "Entities.hpp"

src/NPCManager.hpp

@@ -2,7 +2,6 @@
 
 #include "core/Core.hpp"
 #include "PlayerManager.hpp"
-#include "NPC.hpp"
 #include "Transport.hpp"
 
 #include "JSON.hpp"