Add queue

Signed-off-by: Sven Haardiek <sven@haardiek.de>

queue.go

@@ -0,0 +1,19 @@
+package datastructures
+
+// Queue is a basic implementation of a queue.
+//
+// For more information the data structure take a look at
+// https://en.wikipedia.org/wiki/Queue_(abstract_data_type)
+type Queue struct {
+	dll *DoubleLinkedList
+}
+
+// Enqueue add and element to the queue.
+func (q Queue) Enqueue(element interface{}) {
+	q.dll.Append(element)
+}
+
+// Dequeue get the last element from the queue and removes it.
+func (q Queue) Dequeue() interface{} {
+	return q.dll.Pop(0)
+}