add csproj for svelto framework

.gitignore

@@ -2,3 +2,6 @@
 /EntitySystem/note.txt.meta
 /*.meta
 *.meta
+/obj
+/bin/Release/netstandard2.0
+/bin/Debug/netstandard2.0

Svelto.ECS.csproj

@@ -0,0 +1,23 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="System.Reflection" Version="4.3.0" />
+    <PackageReference Include="System.Reflection.Emit" Version="4.3.0" />
+    <PackageReference Include="System.Reflection.Emit.ILGeneration" Version="4.3.0" />
+    <PackageReference Include="System.Reflection.Emit.Lightweight" Version="4.3.0" />
+    <PackageReference Include="System.Reflection.Extensions" Version="4.3.0" />
+    <PackageReference Include="System.Reflection.Primitives" Version="4.3.0" />
+    <PackageReference Include="System.Reflection.TypeExtensions" Version="4.4.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Reference Include="System.Reflection.Emit.Lightweight">
+      <HintPath>C:\Program Files\dotnet\sdk\NuGetFallbackFolder\microsoft.netcore.app\2.0.0\ref\netcoreapp2.0\System.Reflection.Emit.Lightweight.dll</HintPath>
+    </Reference>
+  </ItemGroup>
+
+</Project>