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/POM-changes.patch

@@ -106,9 +106,10 @@ index 31b8f93e..360d2f08 100644
              <plugin>
                  <groupId>org.apache.maven.plugins</groupId>
 @@ -0,0 +0,0 @@
+                     </dependency>
                  </dependencies>
              </plugin>
-             <plugin>
+-            <plugin>
 -                <groupId>org.codehaus.mojo</groupId>
 -                <artifactId>animal-sniffer-maven-plugin</artifactId>
 -                <version>1.15</version>
@@ -128,10 +129,9 @@ index 31b8f93e..360d2f08 100644
 -                    </signature>
 -                </configuration>
 -            </plugin>
--            <plugin>
+             <plugin>
                  <groupId>org.apache.maven.plugins</groupId>
                  <artifactId>maven-shade-plugin</artifactId>
-                 <version>3.0.0</version>
 @@ -0,0 +0,0 @@
                      </execution>
                  </executions>