title: Visual Studio 2015 EDMX model browser and diagram is missing
body: <p>I have recently updated to Visual Studio 2015. Opened up my solution and works. Till I decided to add in an entity to my edmx. So I double-clicked on the edmx file to open the diagram like it should or maybe the model browser at least but it only opens an XML page. I checked any missed installation from the setup but didn't find anything about entity framework there. I tried to create a test solution and create another edmx but ADO.NET entity is  missing as well. What is going on? Am I going to revert back to Visual studio 2013?</p>