Update references

ILSpy.AddIn/Commands/OpenILSpyCommand.cs

@@ -6,9 +6,9 @@ using System.IO;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
-using EnvDTE80;
 using Microsoft.VisualStudio.Shell;
 using Mono.Cecil;
+using DTEConstants = EnvDTE.Constants;
 
 namespace ICSharpCode.ILSpy.AddIn.Commands
 {
@@ -98,7 +98,7 @@ namespace ICSharpCode.ILSpy.AddIn.Commands
 		protected EnvDTE.Project FindProject(IEnumerable<EnvDTE.Project> projects, string projectFile)
 		{
 			foreach (var project in projects) {
-				if (project.Kind == ProjectKinds.vsProjectKindSolutionFolder) {
+				if (project.Kind == DTEConstants.vsProjectKindSolutionItems) {
 					// This is a solution folder -> search in sub-projects
 					var subProject = FindProject(
 						project.ProjectItems.OfType<EnvDTE.ProjectItem>().Select(pi => pi.SubProject).OfType<EnvDTE.Project>(), 

ILSpy.AddIn/ILSpy.AddIn.csproj

@@ -51,9 +51,11 @@
     <PackageReference Include="Microsoft.VisualStudio.ComponentModelHost" Version="15.6.27413" />
     <PackageReference Include="Microsoft.VisualStudio.Editor" Version="15.6.27740" />
     <PackageReference Include="Microsoft.VisualStudio.LanguageServices" Version="2.4.0" />
-    <PackageReference Include="Microsoft.VisualStudio.Shell.14.0" Version="14.3.25407" />
+    <PackageReference Include="Microsoft.VisualStudio.Shell.15.0" Version="15.6.27413" />
+    <PackageReference Include="Microsoft.VisualStudio.Shell.Interop.14.0.DesignTime" Version="14.3.26929" />
     <PackageReference Include="Microsoft.VisualStudio.Text.UI" Version="15.6.27740" />
     <PackageReference Include="Microsoft.VisualStudio.Text.UI.Wpf" Version="15.6.27740" />
+    <PackageReference Include="Microsoft.VisualStudio.Threading" Version="15.6.56" />
     <PackageReference Include="Mono.Cecil" Version="0.10.1" />
     <PackageReference Include="VSLangProj" Version="7.0.3301" />
   </ItemGroup>