Edited Issue: Designer: Extensions cannot be written using net40 [1161]

For VS11 RTM, Microsoft.Data.Entity.Design.Extensibility.dll was compiled against .NET Framework 4.0. Most sample designer extensions I've seen also target net40.

The latest version of Microsoft.Data.Entity.Design.Extensibility is compiled against .NET Framework 4.5. This causes an error that manifests in one of two ways:

* For existing projects, the assembly cannot be found, "The referenced component 'Microsoft.Data.Entity.Design.Extensibility' could not be found."
* For new projects targeting net40, Microsoft.Data.Entity.Design.Extensibility not longer appears under Assemblies > Extensions in Reference Manager.