Added loop protection to `layoutNetwork`

lib/network/modules/LayoutEngine.js

@@ -188,6 +188,7 @@ class LayoutEngine {
 
       // if less than half of the nodes have a predefined position we continue
       if (positionDefined < 0.5 * this.body.nodeIndices.length) {
+        let MAX_LEVELS = 200;
         let levels = 0;
         let clusterThreshold = 100;
         // if there are a lot of nodes, we cluster before we run the algorithm.
@@ -204,7 +205,7 @@ class LayoutEngine {
               this.body.modules.clustering.clusterOutliers();
             }
             let after = this.body.nodeIndices.length;
-            if (before == after && levels % 3 !== 0) {
+            if ((before == after && levels % 3 !== 0) || levels > MAX_LEVELS) {
               this._declusterAll();
               console.info("This network could not be positioned by this version of the improved layout algorithm.");
               return;