Updated to .NET Standard for compatability.

Author: Oren (electricessence)

Open.Hierarchy.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp1.1</TargetFramework>
+    <TargetFramework>netstandard2.0</TargetFramework>
     <GeneratePackageOnBuild>True</GeneratePackageOnBuild>
     <Authors>electricessence</Authors>
     <Company>electricessence</Company>
@@ -14,6 +14,8 @@ Part of the "Open" set of libraries.</Description>
     <RepositoryUrl>https://github.com/electricessence/Open.Hierarchy/</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
     <PackageTags>dotnet, dotnetcore, cs, tree, node, hierarchy, parent, child, root</PackageTags>
+    <Version>1.1.0</Version>
+    <PackageReleaseNotes>Updated to .NET Standard for compatability.</PackageReleaseNotes>
   </PropertyGroup>
 
   <ItemGroup>
@@ -23,8 +25,9 @@ Part of the "Open" set of libraries.</Description>
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Open.Disposable" Version="1.0.4" />
-    <PackageReference Include="Open.Disposable.ObjectPools" Version="1.2.0" />
+    <PackageReference Include="Open.Disposable" Version="1.1.0" />
+    <PackageReference Include="Open.Disposable.ObjectPools" Version="1.3.0" />
+    <PackageReference Include="Open.Numeric" Version="1.1.0" />
   </ItemGroup>
 
 </Project>