fixed springs not calculating. added example, set inherit color to default ON

lib/network/Network.js

@@ -107,7 +107,7 @@ function Network (container, data, options) {
         gap: 5,
         altLength: undefined
       },
-      inheritColor: false // to, from, false, true (== from)
+      inheritColor: "from" // to, from, false, true (== from)
     },
     configurePhysics:false,
     physics: {

lib/network/mixins/physics/PhysicsMixin.js

@@ -95,7 +95,7 @@ exports._calculateForces = function () {
   this._calculateGravitationalForces();
   this._calculateNodeForces();
 
-  if (this.constants.springConstant > 0) {
+  if (this.constants.physics.springConstant > 0) {
     if (this.constants.smoothCurves.enabled == true && this.constants.smoothCurves.dynamic == true) {
       this._calculateSpringForcesWithSupport();
     }