Added load order restrictions for DependencyAttribute

Abstracted dependency manager away as an interface

Torch.API/Managers/IDependencyProvider.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Torch.API.Managers
+{
+    public interface IDependencyProvider
+    {
+        /// <summary>
+        /// Gets the manager that provides the given type.  If there is no such manager, returns null.
+        /// </summary>
+        /// <param name="type">Type of manager</param>
+        /// <returns>manager, or null if none exists</returns>
+        IManager GetManager(Type type);
+    }
+
+    public static class DependencyProviderExtensions
+    {
+        /// <summary>
+        /// Gets the manager that provides the given type.  If there is no such manager, returns null.
+        /// </summary>
+        /// <typeparam name="T">Type of manager</typeparam>
+        /// <returns>manager, or null if none exists</returns>
+        public static T GetManager<T>(this IDependencyProvider depProvider) where T : class, IManager
+        {
+            return (T)depProvider.GetManager(typeof(T));
+        }
+    }
+
+}