Cross target netcoreapp2.1

src/ImageSharp/ImageSharp.csproj

@@ -5,7 +5,7 @@
     <VersionPrefix Condition="$(packageversion) != ''">$(packageversion)</VersionPrefix>
     <VersionPrefix Condition="$(packageversion) == ''">0.0.1</VersionPrefix>
     <Authors>Six Labors and contributors</Authors>
-    <TargetFrameworks>netstandard1.1;netstandard1.3;netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>netstandard1.1;netstandard1.3;netstandard2.0;netcoreapp2.1</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <AssemblyName>SixLabors.ImageSharp</AssemblyName>
@@ -29,7 +29,7 @@
     <DebugType Condition="$(codecov) == ''">portable</DebugType>
     <DebugSymbols>True</DebugSymbols>
     <Features>IOperation</Features>
-    <LangVersion>7.2</LangVersion>
+    <LangVersion>7.3</LangVersion>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="..\Shared\*.cs" Exclude="bin\**;obj\**;**\*.xproj;packages\**" />
@@ -40,10 +40,14 @@
     <PackageReference Include="StyleCop.Analyzers" Version="1.1.0-beta007">
       <PrivateAssets>All</PrivateAssets>
     </PackageReference>
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.5.0" />
+  </ItemGroup>
+
+  <ItemGroup Condition=" '$(TargetFramework)' != 'netcoreapp2.1'">
     <PackageReference Include="System.Buffers" Version="4.5.0" />
     <PackageReference Include="System.Memory" Version="4.5.0" />
-    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.5.0" />
   </ItemGroup>
+  
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard1.1' OR '$(TargetFramework)' == 'netstandard1.3'">
     <PackageReference Include="System.IO.Compression" Version="4.3.0" />
     <PackageReference Include="System.Threading.Tasks.Parallel" Version="4.3.0" />