Refactor folder stucture

Needlework.Net/Extensions/ServiceCollectionExtensions.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Needlework.Net.Extensions
+{
+    public static class ServiceCollectionExtensions
+    {
+        public static IServiceCollection AddSingletonsFromAssemblies<T>(this ServiceCollection services)
+        {
+            var types = AppDomain.CurrentDomain.GetAssemblies()
+                .SelectMany(s => s.GetTypes())
+                .Where(p => !p.IsAbstract && typeof(T).IsAssignableFrom(p));
+
+            foreach (var type in types) services.AddSingleton(typeof(T), type);
+
+            return services;
+        }
+    }
+}