restructure and add ipi texs

ws2019/ipi/uebungen/cpp_headers/Queue.hh

@@ -0,0 +1,20 @@
+template<class T>
+class Queue : public DLList<T> {
+public :
+  // Default-Konstruktoren + Zuweisung OK
+  bool empty () {
+    return DLList<T>::empty();
+  }
+  T front () {
+    return *DLList<T>::begin();
+  }
+  T back () {
+    return *DLList<T>::rbegin();
+  }
+  void push (T t) {
+    this->insert(DLList<T>::end(),t);
+  }
+  void pop () {
+    this->erase(DLList<T>::begin());
+  }
+} ;