title: Edmx designer and item template missing from VS2012
body: <p>I am nearly sure this was available and working before, but at this site I have a very recent upgrade from VS2010 to VS2012. I find that if I double click an .edmx file, it by default opens in an XML editor. Also, the Enterprise Data Model item template is missing, so I must open the project in VS2010 just to add a new data model. Are there any known issues that could cause this?</p>