Cleanup and ref update.

Author: Oren (electricessence)

Node.Factory.cs

@@ -18,12 +18,9 @@ public Factory()
 					() => new Node<T>(this), PrepareForPool, null, ushort.MaxValue);
 			}
 
-			protected override void OnDispose(bool calledExplicitly)
+			protected override void OnDispose()
 			{
-				if (calledExplicitly)
-				{
-					DisposeOf(ref _pool);
-				}
+				DisposeOf(ref _pool);
 			}
 
 			ConcurrentQueueObjectPool<Node<T>> _pool;
@@ -35,7 +32,7 @@ protected override void OnDispose(bool calledExplicitly)
 			public Node<T> GetBlankNode()
 			{
 				var p = _pool;
-				AssertIsAlive();
+				this.AssertIsAlive();
 
 				var n = p.Take();
 				n._recycled = false;

Open.Hierarchy.csproj

@@ -1,22 +1,23 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netstandard2.0;netstandard2.1</TargetFrameworks>
     <GeneratePackageOnBuild>True</GeneratePackageOnBuild>
     <Authors>electricessence</Authors>
     <Company>electricessence</Company>
     <Description>Interfaces and classes helful in managing tree-like data structures. 
 
 Part of the "Open" set of libraries.</Description>
     <Copyright>https://github.com/electricessence/Open.Hierarchy/blob/master/LICENSE</Copyright>
-    <PackageLicenseUrl>https://github.com/electricessence/Open.Hierarchy/blob/master/LICENSE</PackageLicenseUrl>
+    <PackageLicenseUrl></PackageLicenseUrl>
     <PackageProjectUrl>https://github.com/electricessence/Open.Hierarchy/</PackageProjectUrl>
     <RepositoryUrl>https://github.com/electricessence/Open.Hierarchy/</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
     <PackageTags>dotnet, dotnetcore, cs, tree, node, hierarchy, parent, child, root</PackageTags>
-    <Version>1.5.1</Version>
+    <Version>1.6.1</Version>
     <PackageReleaseNotes>Improved API.  Implemented IList&lt;Node&lt;T&gt;&gt; for all nodes.
 Validated mapping optimization.</PackageReleaseNotes>
+    <PackageLicenseExpression>MIT</PackageLicenseExpression>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
@@ -34,9 +35,7 @@ Validated mapping optimization.</PackageReleaseNotes>
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Open.Disposable" Version="1.2.1" />
-    <PackageReference Include="Open.Disposable.ObjectPools" Version="2.1.3" />
-    <PackageReference Include="Open.Numeric" Version="1.2.1" />
+    <PackageReference Include="Open.Disposable.ObjectPools" Version="2.3.2" />
   </ItemGroup>
 
 </Project>