Remove null values in TileEntity tick list

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

Spigot-API-Patches/add-Trove-and-FastUtil-to-Bukkit.patch

@@ -5,13 +5,14 @@ Subject: [PATCH] add Trove and FastUtil to Bukkit
 
 
 diff --git a/pom.xml b/pom.xml
-index 07143b46..1e57d386 100644
+index 360d2f08..c6bdf44e 100644
 --- a/pom.xml
 +++ b/pom.xml
 @@ -0,0 +0,0 @@
+     </repositories>
  
      <dependencies>
-         <dependency>
++        <dependency>
 +            <groupId>net.sf.trove4j</groupId>
 +            <artifactId>trove4j</artifactId>
 +            <version>3.0.3</version>
@@ -24,8 +25,7 @@ index 07143b46..1e57d386 100644
 +            <version>1.0</version>
 +            <scope>provided</scope>
 +        </dependency>
-+        <dependency>
+         <dependency>
              <groupId>commons-lang</groupId>
              <artifactId>commons-lang</artifactId>
-             <version>2.6</version>
 --