Change .NET version of mpu.exe from 3.5 to 4.6.

This is required to async serializer generation,
and there are no reasons to remain .NET 3.5 now.

Author: yfakariya

src/mpu/mpu.csproj

@@ -9,10 +9,11 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>mpu</RootNamespace>
     <AssemblyName>mpu</AssemblyName>
-    <TargetFrameworkVersion>v3.5</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
     <RestorePackages>true</RestorePackages>
+    <TargetFrameworkProfile />
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <PlatformTarget>AnyCPU</PlatformTarget>
@@ -23,6 +24,7 @@
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <PlatformTarget>AnyCPU</PlatformTarget>
@@ -32,6 +34,7 @@
     <DefineConstants>TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
@@ -53,6 +56,7 @@
     <Compile Include="SerializerTargetCompiler.cs" />
   </ItemGroup>
   <ItemGroup>
+    <None Include="app.config" />
     <None Include="packages.config" />
   </ItemGroup>
   <ItemGroup>