changed edgewidth when zooming, scale normally with min width of 0.3 px

lib/network/Edge.js

@@ -309,14 +309,14 @@ Edge.prototype._drawLine = function(ctx) {
  */
 Edge.prototype._getLineWidth = function() {
   if (this.selected == true) {
-    return Math.min(this.widthSelected, this.options.widthMax)*this.networkScaleInv;
+    return  Math.max(Math.min(this.widthSelected, this.options.widthMax), 0.3*this.networkScaleInv);
   }
   else {
     if (this.hover == true) {
-      return Math.min(this.options.hoverWidth, this.options.widthMax)*this.networkScaleInv;
+      return Math.max(Math.min(this.options.hoverWidth, this.options.widthMax), 0.3*this.networkScaleInv);
     }
     else {
-      return this.options.width*this.networkScaleInv;
+      return Math.max(this.options.width, 0.3*this.networkScaleInv);
     }
   }
 };