add support for .NET Portable Subset #180 https://github.com/fsprojects/Paket/issues/180

XmenCore.fsproj

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
  <PropertyGroup>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
    <SchemaVersion>2.0</SchemaVersion>
    <ProjectGuid>a5726914-661b-4f63-afe5-c6a07df2e33a</ProjectGuid>
    <OutputType>Library</OutputType>
    <RootNamespace>Xmen.Core</RootNamespace>
    <AssemblyName>Xmen.Core</AssemblyName>
    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
    <TargetFrameworkProfile>Profile7</TargetFrameworkProfile>
    <TargetProfile>netcore</TargetProfile>
    <TargetFSharpCoreVersion>3.3.1.0</TargetFSharpCoreVersion>
    <Name>XmenCore</Name>
    <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
    <DebugSymbols>true</DebugSymbols>
    <DebugType>full</DebugType>
    <Optimize>false</Optimize>
    <Tailcalls>true</Tailcalls>
    <OutputPath>bin\Debug\</OutputPath>
    <DefineConstants>DEBUG;TRACE</DefineConstants>
    <WarningLevel>3</WarningLevel>
    <DocumentationFile>bin\Debug\Xmen.Core.XML</DocumentationFile>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
    <DebugType>pdbonly</DebugType>
    <Optimize>true</Optimize>
    <Tailcalls>true</Tailcalls>
    <OutputPath>bin\Release\</OutputPath>
    <DefineConstants>TRACE</DefineConstants>
    <WarningLevel>3</WarningLevel>
    <DocumentationFile>bin\Release\Xmen.Core.XML</DocumentationFile>
  </PropertyGroup>
  <PropertyGroup>
    <MinimumVisualStudioVersion Condition="'$(MinimumVisualStudioVersion)' == ''">12</MinimumVisualStudioVersion>
  </PropertyGroup>
  <Import Project="$(MSBuildExtensionsPath32)\..\Microsoft SDKs\F#\3.1\Framework\v4.0\Microsoft.Portable.FSharp.Targets" />
  <Import Project="$(SolutionDir)\.nuget\NuGet.targets" Condition="Exists('$(SolutionDir)\.nuget\NuGet.targets')" />
  <ItemGroup>
    <Compile Include="Utilities.fs" />
    <Compile Include="Array.fs" />
    <Compile Include="List.fs" />
    <None Include="List.fsx" />
    <Compile Include="Seq.fs" />
    <Compile Include="Extentions.fs" />
    <Compile Include="Json.fs" />
    <Content Include="paket.references" />
  </ItemGroup>
  <ItemGroup>
    <Reference Include="FSharp.Core">
      <Name>FSharp.Core</Name>
      <AssemblyName>FSharp.Core.dll</AssemblyName>
      <HintPath>$(MSBuildExtensionsPath32)\..\Reference Assemblies\Microsoft\FSharp\.NETCore\$(TargetFSharpCoreVersion)\FSharp.Core.dll</HintPath>
    </Reference>
  </ItemGroup>
  <Import Project="$(SolutionDir)\.paket\paket.targets" />
  <Choose>
    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And $(TargetFrameworkVersion) == 'v2.0'">
      <ItemGroup>
        <Reference Include="Newtonsoft.Json">
          <HintPath>..\..\packages\Newtonsoft.Json\lib\net20\Newtonsoft.Json.dll</HintPath>
          <Private>True</Private>
          <Paket>True</Paket>
        </Reference>
      </ItemGroup>
    </When>
    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And $(TargetFrameworkVersion) == 'v3.5'">
      <ItemGroup>
        <Reference Include="Newtonsoft.Json">
          <HintPath>..\..\packages\Newtonsoft.Json\lib\net35\Newtonsoft.Json.dll</HintPath>
          <Private>True</Private>
          <Paket>True</Paket>
        </Reference>
      </ItemGroup>
    </When>
    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And $(TargetFrameworkVersion) == 'v4.0'">
      <ItemGroup>
        <Reference Include="Newtonsoft.Json">
          <HintPath>..\..\packages\Newtonsoft.Json\lib\net40\Newtonsoft.Json.dll</HintPath>
          <Private>True</Private>
          <Paket>True</Paket>
        </Reference>
      </ItemGroup>
    </When>
    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And $(TargetFrameworkVersion) == 'v4.5'">
      <ItemGroup>
        <Reference Include="Newtonsoft.Json">
          <HintPath>..\..\packages\Newtonsoft.Json\lib\net45\Newtonsoft.Json.dll</HintPath>
          <Private>True</Private>
          <Paket>True</Paket>
        </Reference>
      </ItemGroup>
    </When>
    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework'">
      <ItemGroup>
        <Reference Include="Newtonsoft.Json">
          <HintPath>..\..\packages\Newtonsoft.Json\lib\net45\Newtonsoft.Json.dll</HintPath>
          <Private>True</Private>
          <Paket>True</Paket>
        </Reference>
      </ItemGroup>
    </When>
  </Choose>
</Project>