Build: fix 'test quick' test category filter

build.fsx

@@ -492,7 +492,7 @@ Target "DataBuild" (fun _ -> build !! "MathNet.Numerics.Data.sln")
 // --------------------------------------------------------------------------------------
 
 let test target =
-    let quick p = if hasBuildParam "quick" then { p with Where="!~LongRunning" } else p
+    let quick p = if hasBuildParam "quick" then { p with Where="cat!=LongRunning" } else p
     NUnit3 (fun p ->
         { p with
             ShadowCopy = false

src/UnitTests/UnitTests-Net35.csproj

@@ -58,7 +58,7 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
-    <Reference Include="System.Core"/>
+    <Reference Include="System.Core" />
     <Reference Include="System.Runtime.Serialization" />
     <Reference Include="System.XML" />
   </ItemGroup>