Fix major bug in layout iteration

Layout.js

@@ -125,11 +125,15 @@ class Layout {
         if (obj.offsetCollides(offset)) {
           continue;
         }
-        obj.savePos();
+        for (let obj of objects) {
+          obj.savePos();
+        }
         obj.moveBy(offset);
         this.setTension(objects);
         let testTension = this.getTotalTension(objects);
-        obj.restorePos();
+        for (let obj of objects) {
+          obj.restorePos();
+        }
         if (testTension < baseTension) {
           obj.moveBy(offset);
           return true;

LayoutGroup.js

@@ -35,18 +35,11 @@ class LayoutGroup {
   }
 
   savePos() {
-    for (let node of this.nodes) {
-      node.savePos();
-    }
+    this.savedVec_ = Array.from(this.vec);
   }
 
   restorePos() {
-    for (let node of this.nodes) {
-      node.restorePos();
-    }
-    for (let node of this.nodes) {
-      this.nodesByPos_.set(node.pos, node);
-    }
+    this.vec = this.savedVec_;
   }
 
   moveBy(offset) {

LayoutNode.js

@@ -132,10 +132,12 @@ class LayoutNode {
 
   savePos() {
     this.savedPos_ = this.pos;
+    this.savedVec_ = Array.from(this.vec);
   }
 
   restorePos() {
     this.moveTo(this.savedPos_);
+    this.vec = this.savedVec_;
   }
 
   getStep() {