Change method visibility to allow custom placement strategies outside of package (issue #45).

Author: brunomnsilva

src/main/java/com/brunomnsilva/smartgraph/graphview/SmartGraphPanel.java

@@ -434,15 +434,15 @@ public Graph<V, E> getModel() {
      * Returns a collection of the smart vertices that represent the underlying model vertices.
      * @return a collection of the smart vertices
      */
-    protected final Collection<SmartGraphVertex<V>> getSmartVertices() {
+    public final Collection<SmartGraphVertex<V>> getSmartVertices() {
         return new ArrayList<>(this.vertexNodes.values());
     }
 
     /**
      * Returns a collection of the smart edges that represent the underlying model edges.
      * @return a collection of the smart edges
      */
-    protected final Collection<SmartGraphEdge<E, V>> getSmartEdges() {
+    public final Collection<SmartGraphEdge<E, V>> getSmartEdges() {
         return new ArrayList<>(this.edgeNodes.values());
     }