Max Zoom 2x (#106)

src/view.js

@@ -451,7 +451,7 @@ class View {
     
         // Set up zoom support
         var zoom = d3.zoom();
-        zoom.scaleExtent([0.1, 1]);
+        zoom.scaleExtent([0.1, 2]);
         zoom.on('zoom', (e) => {
             d3.select(outputGroup).attr('transform', d3.event.transform);
         });