anchor.diff:  let bt =
       BuildTool().PackageId("WebSharper.Piglets")
           .VersionFrom("WebSharper")
  +        .WithFSharpVersion(FSharpVersion.FSharp30)
           .WithFramework(fun fw -> fw.Net40)
   
   let main =
  
positive.code:         .SourcesFromProject()
          .References(fun r ->
              [
                  r.NuGet("IntelliFactory.Reactive").Reference()
              ])
  
  let test =
  
negative.code:         .References(fun r ->
              [
                  r.NuGet("IntelliFactory.Reactive").Reference()
                  r.NuGet("WebSharper.Html").Reference()
                  r.Project(main)
              ])
  
  