Remove null values in TileEntity tick list

Because who wouldn't want to tick a null tile entity right?
Fixes GH-851

Spigot-Server-Patches/0187-String-based-Action-Bar-API.patch

@@ -1,4 +1,4 @@
-From a11dd5b2bf084b3497007431eb7359db479f5d0b Mon Sep 17 00:00:00 2001
+From d5090572a893a013cb7485d6ca040cc46d66eff6 Mon Sep 17 00:00:00 2001
 From: Aikar <aikar@aikar.co>
 Date: Tue, 27 Dec 2016 15:02:42 -0500
 Subject: [PATCH] String based Action Bar API
@@ -62,13 +62,14 @@ index 1159eea1..38359517 100644
 +    }
  }
 diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
-index 2569f0b7..28e00da3 100644
+index b65ac0c7..005c8a00 100644
 --- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
 +++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
-@@ -172,6 +172,18 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
+@@ -171,6 +171,18 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
+     }
  
      // Paper start
-     @Override
++    @Override
 +    public void sendActionBar(String message) {
 +        if (getHandle().playerConnection == null || message == null || message.isEmpty()) return;
 +        getHandle().playerConnection.sendPacket(new PacketPlayOutChat(new ChatComponentText(message), ChatMessageType.GAME_INFO));
@@ -80,10 +81,9 @@ index 2569f0b7..28e00da3 100644
 +        sendActionBar(org.bukkit.ChatColor.translateAlternateColorCodes(alternateChar, message));
 +    }
 +
-+    @Override
+     @Override
      public void setPlayerListHeaderFooter(BaseComponent[] header, BaseComponent[] footer) {
          PacketPlayOutPlayerListHeaderFooter packet = new PacketPlayOutPlayerListHeaderFooter();
-         packet.header = header;
 -- 
-2.13.1.windows.2
+2.14.1