Add player affects spawning API

Test plugin here: https://github.com/Zbob750/AffectsSpawning
I believe this originated with SportBukkit, slightly modified for our (and potentially upstream's) usage

Spigot-API-Patches/0004-Player-affects-spawning-API.patch

@@ -0,0 +1,41 @@
+From 759908be8944103e051eefd95710f9dfe39b532e Mon Sep 17 00:00:00 2001
+From: Jedediah Smith <jedediah@silencegreys.com>
+Date: Fri, 8 Aug 2014 22:51:26 -0500
+Subject: [PATCH] Player affects spawning API
+
+
+diff --git a/src/main/java/org/bukkit/entity/Player.java b/src/main/java/org/bukkit/entity/Player.java
+index b2ad5b7..b2a8e2e 100644
+--- a/src/main/java/org/bukkit/entity/Player.java
++++ b/src/main/java/org/bukkit/entity/Player.java
+@@ -1102,6 +1102,28 @@ public interface Player extends HumanEntity, Conversable, CommandSender, Offline
+         {
+             throw new UnsupportedOperationException( "Not supported yet." );
+         }
++
++        /**
++         * Get whether the player affects mob spawning
++         *
++         * @return whether or not the player affects
++         * mob spawning.
++         */
++        public boolean getAffectsSpawning()
++        {
++            throw new  UnsupportedOperationException( "Not supported yet." );
++        }
++
++        /**
++         * Set whether or not the player affects mob spawning
++         *
++         * @param affects whether or not the player should affect
++         * spawning or not.
++         */
++        public void setAffectsSpawning(boolean affects)
++        {
++            throw new UnsupportedOperationException( "Not supported yet" );
++        }
+     }
+ 
+     Spigot spigot();
+-- 
+1.9.1