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/String-based-Action-Bar-API.patch

@@ -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
 @@ -0,0 +0,0 @@ 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));
@@ -80,8 +81,7 @@ 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;
 --