Use the molecule name in NodeTracker, not its toString

alchemist/alchemist-swingui/src/main/java/it/unibo/alchemist/boundary/monitors/NodeTracker.java

@@ -78,7 +78,7 @@ public void stepDone(final Environment<T> env, final Reaction<T> exec, final Tim
             sb.append(CONTENT);
             sb.append('\n');
             sb.append(n.getContents().entrySet().stream()
-                .map(e -> e.getKey() + " > " + e.getValue() + '\n')
+                .map(e -> e.getKey().getName() + " > " + e.getValue() + '\n')
                 .sorted()
                 .collect(Collectors.joining())
             );