Refactoring

- changed to maven
- modified hashMap and HashSet to Tree
- modified files path

src/main/java/berack96/lib/graph/visit/VisitMST.java

@@ -0,0 +1,20 @@
+package berack96.lib.graph.visit;
+
+import berack96.lib.graph.Edge;
+
+import java.util.Set;
+
+/**
+ * @param <V>
+ */
+public interface VisitMST<V> extends VisitStrategy<V> {
+
+    /**
+     * Return the latest calculated MST.<br>
+     * https://en.wikipedia.org/wiki/Minimum_spanning_tree
+     *
+     * @return the latest MST
+     * @throws NullPointerException if there is no last calculated MST
+     */
+    Set<Edge<V>> getMST();
+}