Revert "totalngram: use CircularFifoQueue as sliding window base"

Seems to be a lot slower than with LinkedList, strange.

This reverts commit 73203b7c8a57731fdb7e76dce90034df7ffb88d8.
diff --git a/pom.xml b/pom.xml
index 308e1c2..97ca101 100644
--- a/pom.xml
+++ b/pom.xml
@@ -150,11 +150,5 @@
             <artifactId>etaprinter</artifactId>
             <version>2.0.0</version>
         </dependency>
-        <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-collections4 -->
-        <dependency>
-            <groupId>org.apache.commons</groupId>
-            <artifactId>commons-collections4</artifactId>
-            <version>4.1</version>
-        </dependency>
     </dependencies>
 </project>
\ No newline at end of file
diff --git a/src/main/java/org/ids_mannheim/SlidingWindowQueue.java b/src/main/java/org/ids_mannheim/SlidingWindowQueue.java
index cf3db43..4f07362 100644
--- a/src/main/java/org/ids_mannheim/SlidingWindowQueue.java
+++ b/src/main/java/org/ids_mannheim/SlidingWindowQueue.java
@@ -1,22 +1,22 @@
 package org.ids_mannheim;
 
+import java.util.LinkedList;
 import java.util.function.Consumer;
-import org.apache.commons.collections4.queue.CircularFifoQueue;
 
-public class SlidingWindowQueue extends  CircularFifoQueue {
+public class SlidingWindowQueue extends LinkedList {
     private final int maxSize;
     private final Consumer<String> flush;
 
     public SlidingWindowQueue(int size, Consumer<String> flush) {
-        super(size);
         this.maxSize = size;
         this.flush = flush;
     }
 
     public boolean add(String k) {
         boolean r = super.add(k);
-        if (isAtFullCapacity()) {
+        if (size() == maxSize) {
             this.flush.accept(String.join(" ", this));
+            remove(0);
         }
         return r;
     }