Fix TestFramework clone project (#238)

***NO_CI***

(cherry picked from commit e27a6b6)

Author: josesimoes

Tests/TestFramework/TestFramework.nfproj

@@ -30,15 +30,13 @@
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\Assert.cs" />
-    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\Assert.AreEqual.cs" />
-    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\Assert.AreNotEqual.cs" />
-    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\Assert.Obsolete.cs" />
-    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\CallerArgumentExpressionAttribute.cs" />
-    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\CollectionAssert.cs" />
-    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\NullableAttributes.cs" />
-    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\OutputHelper.cs" />
-    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\TestExtensions.cs" />
+    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\Assert.cs" Link="Assert.cs"/>
+    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\Assert.AreEqual.cs" Link="Assert.AreEqual.cs"/>
+    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\Assert.AreNotEqual.cs" Link="Assert.AreNotEqual.cs"/>
+    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\Assert.Obsolete.cs" Link="\Assert.Obsolete.cs"/>
+    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\CollectionAssert.cs" Link="CollectionAssert.cs"/>
+    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\OutputHelper.cs" Link="OutputHelper.cs"/>
+    <Compile Include="..\..\nanoFramework.TestFramework\source\TestFramework\TestExtensions.cs" Link="TestExtensions.cs"/>
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\nanoFramework.CoreLibrary\CoreLibrary.nfproj" />
@@ -50,4 +48,4 @@
       <ProjectConfigurationsDeclaredAsItems />
     </ProjectCapabilities>
   </ProjectExtensions>
-</Project>
+</Project>