Horses spawned under Y 0 cause CraftBukkit to crash. This happens a lot since people keep using bugged Horses for Holographics

Remove out of bounds horses, fixes an vanilla bug. Fixes SPIGOT-58

nms-patches/EntityHorse.patch

@@ -1,5 +1,5 @@
---- ../work/decompile-8eb82bde//net/minecraft/server/EntityHorse.java	2014-11-28 17:43:43.101707435 +0000
-+++ src/main/java/net/minecraft/server/EntityHorse.java	2014-11-28 17:38:22.000000000 +0000
+--- ../work/decompile-8eb82bde//net/minecraft/server/EntityHorse.java	Sun Nov 30 00:00:30 2014
++++ src/main/java/net/minecraft/server/EntityHorse.java	Sun Nov 30 00:00:14 2014
 @@ -4,6 +4,8 @@
  import java.util.Iterator;
  import java.util.List;
@@ -61,12 +61,12 @@
          }
 +        // CraftBukkit end */
 +    }
- 
++
 +    // CraftBukkit start - Add method
 +    @Override
 +    protected void dropDeathLoot(boolean flag, int i) {
 +        super.dropDeathLoot(flag, i);
-+
+ 
 +        // Moved from die method above
 +        if (!this.world.isStatic) {
 +            this.dropChest();
@@ -85,7 +85,21 @@
              }
  
              if (!this.cw() && this.passenger == null && this.random.nextInt(300) == 0 && this.world.getType(new BlockPosition(MathHelper.floor(this.locX), MathHelper.floor(this.locY) - 1, MathHelper.floor(this.locZ))).getBlock() == Blocks.GRASS) {
-@@ -949,6 +965,7 @@
+@@ -730,6 +746,13 @@
+     }
+ 
+     public void s_() {
++        // CraftBukkit start - Remove out of bounds horses, fixes an vanilla bug
++        if ( this.locY < -600 ) {
++            die();
++            return;
++        }
++        // CraftBukkit end
++
+         super.s_();
+         if (this.world.isStatic && this.datawatcher.a()) {
+             this.datawatcher.e();
+@@ -949,6 +972,7 @@
          nbttagcompound.setInt("Temper", this.getTemper());
          nbttagcompound.setBoolean("Tame", this.isTame());
          nbttagcompound.setString("OwnerUUID", this.getOwnerUUID());
@@ -93,7 +107,7 @@
          if (this.hasChest()) {
              NBTTagList nbttaglist = new NBTTagList();
  
-@@ -1001,6 +1018,12 @@
+@@ -1001,6 +1025,12 @@
              this.setOwnerUUID(s);
          }
  
@@ -106,7 +120,7 @@
          AttributeInstance attributeinstance = this.getAttributeMap().a("Speed");
  
          if (attributeinstance != null) {
-@@ -1166,18 +1189,25 @@
+@@ -1166,18 +1196,25 @@
  
      public void v(int i) {
          if (this.cE()) {