Support addins with subdirectories from the online gallery.

Addin manager now copies all files and subdirectories from the extracted
NuGet package to the temporary addin installation folder.

src/AddIns/Misc/AddInManager2/Project/Src/Model/AddInSetup.cs

@@ -445,26 +445,34 @@ namespace ICSharpCode.AddInManager2.Model
 				{
 					Directory.Delete(targetDir, true);
 				}
-				Directory.CreateDirectory(targetDir);
+				DeepCopy(packageDirectory, targetDir);
-				var packageContentsFiles = Directory.EnumerateFiles(packageDirectory, "*.*", SearchOption.TopDirectoryOnly);
+				
-				if (packageContentsFiles != null)
+				return true;
+			}
+			catch (Exception)
+			{
+				return false;
+			}
+		}
+		
+		void DeepCopy(string packageDirectory, string targetDirectory)
 		{
-					foreach (var file in packageContentsFiles)
+			Directory.CreateDirectory(targetDirectory);
+			
+			foreach (string file in Directory.EnumerateFiles(packageDirectory, "*.*", SearchOption.TopDirectoryOnly))
 			{
 				// Don't copy the .nupkg file
 				FileInfo fileInfo = new FileInfo(file);
 				if (fileInfo.Extension != ".nupkg")
 				{
-							File.Copy(file, Path.Combine(targetDir, fileInfo.Name));
+					File.Copy(file, Path.Combine(targetDirectory, fileInfo.Name));
-						}
 				}
 			}
 			
-				return true;
+			foreach (string packageSubDirectory in Directory.EnumerateDirectories(packageDirectory))
-			}
-			catch (Exception)
 			{
-				return false;
+				string newTargetDirectory = Path.Combine(targetDirectory, Path.GetFileName(packageSubDirectory));
+				DeepCopy(packageSubDirectory, newTargetDirectory);
 			}
 		}