Merge pull request #1911 from maartenbreddels/enable_by_default

for notebook 5.3 you don't need to enable the extensions anymore, solves #1908

Author: jasongrout

README.md

@@ -69,7 +69,7 @@ Install the current version of ipywidgets using pip or conda.
 
 ```
 pip install ipywidgets
-jupyter nbextension enable --py --sys-prefix widgetsnbextension
+jupyter nbextension enable --py --sys-prefix widgetsnbextension  # can be skipped for notebook version 5.3 and above
 ```
 
 - With conda:

widgetsnbextension/setup.py

@@ -205,6 +205,7 @@ def run(self):
                 'widgetsnbextension/static/extension.js',
                 'widgetsnbextension/static/extension.js.map'
         ]),
+        ('etc/jupyter/nbconfig/notebook.d/' , ['widgetsnbextension.json'])
     ],
     zip_safe=False,
     include_package_data = True,

widgetsnbextension/widgetsnbextension.json

@@ -0,0 +1,5 @@
+{
+  "load_extensions": {
+    "jupyter-js-widgets/extension": true
+  }
+}