Reinstall the DiffLib package

ICSharpCode.Decompiler.Tests/ICSharpCode.Decompiler.Tests.csproj

@@ -53,7 +53,7 @@
     <DefineConstants>TRACE</DefineConstants>
   </PropertyGroup>
   <ItemGroup>
-    <Reference Include="DiffLib">
+    <Reference Include="DiffLib, Version=1.0.0.55, Culture=neutral, PublicKeyToken=9e2fabf3af85dba9, processorArchitecture=MSIL">
       <HintPath>..\packages\DiffLib.1.0.0.55\lib\net35-Client\DiffLib.dll</HintPath>
     </Reference>
     <Reference Include="Microsoft.CodeAnalysis, Version=1.3.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">

ICSharpCode.Decompiler.Tests/packages.config

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="DiffLib" version="1.0.0.55" requireReinstallation="true" />
+  <package id="DiffLib" version="1.0.0.55" targetFramework="net461" />
   <package id="Microsoft.CodeAnalysis.Analyzers" version="1.1.0" targetFramework="net45" />
   <package id="Microsoft.CodeAnalysis.Common" version="1.3.2" targetFramework="net45" />
   <package id="Microsoft.CodeAnalysis.CSharp" version="1.3.2" targetFramework="net45" />