Added load order restrictions for DependencyAttribute

Abstracted dependency manager away as an interface

Torch.API/Managers/IDependencyManager.cs

@@ -0,0 +1,88 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Torch.API.Managers
+{
+    /// <summary>
+    /// Manages a set of <see cref="IManager"/> and the dependencies between them.
+    /// </summary>
+    public interface IDependencyManager : IDependencyProvider
+    {
+        /// <summary>
+        /// Registers the given manager into the dependency system.
+        /// </summary>
+        /// <remarks>
+        /// This method only returns false when there is already a manager registered with a type derived from this given manager,
+        /// or when the given manager is derived from an already existing manager.
+        /// </remarks>
+        /// <param name="manager">Manager to register</param>
+        /// <exception cref="InvalidOperationException">When adding a new manager to an initialized dependency manager</exception>
+        /// <returns>true if added, false if not</returns>
+        bool AddManager(IManager manager);
+
+        /// <summary>
+        /// Clears all managers registered with this dependency manager
+        /// </summary>
+        /// <exception cref="InvalidOperationException">When removing managers from an initialized dependency manager</exception>
+        void ClearManagers();
+
+        /// <summary>
+        /// Removes a single manager from this dependency manager.
+        /// </summary>
+        /// <param name="manager">The manager to remove</param>
+        /// <returns>true if successful, false if the manager wasn't found</returns>
+        /// <exception cref="InvalidOperationException">When removing managers from an initialized dependency manager</exception>
+        bool RemoveManager(IManager manager);
+
+        /// <summary>
+        /// Initializes the dependency manager, and all its registered managers.
+        /// </summary>
+        void Init();
+
+        /// <summary>
+        /// Disposes the dependency manager, and all its registered managers.
+        /// </summary>
+        void Dispose();
+
+        /// <summary>
+        /// The order that managers should be loaded in.  (Dependencies, then dependents)
+        /// </summary>
+        /// <exception cref="InvalidOperationException">When trying to determine load order before this dependency manager is initialized</exception>
+        IEnumerable<IManager> LoadOrder { get; }
+
+        /// <summary>
+        /// The order that managers should be unloaded in.  (Dependents, then dependencies)
+        /// </summary>
+        /// <exception cref="InvalidOperationException">When trying to determine unload order before this dependency manager is initialized</exception>
+        IEnumerable<IManager> UnloadOrder { get; }
+    }
+
+    public static class DependencyManagerExtensions
+    {
+        /// <summary>
+        /// Removes a single manager from this dependency manager.
+        /// </summary>
+        /// <param name="managerType">The dependency type to remove</param>
+        /// <returns>The manager that was removed, or null if one wasn't removed</returns>
+        /// <exception cref="InvalidOperationException">When removing managers from an initialized dependency manager</exception>
+        public static IManager RemoveManager(this IDependencyManager depManager, Type managerType)
+        {
+            IManager mgr = depManager.GetManager(managerType);
+            return depManager.RemoveManager(mgr) ? mgr : null;
+        }
+        /// <summary>
+        /// Removes a single manager from this dependency manager.
+        /// </summary>
+        /// <typeparam name="T">The dependency type to remove</typeparam>
+        /// <returns>The manager that was removed, or null if one wasn't removed</returns>
+        /// <exception cref="InvalidOperationException">When removing managers from an initialized dependency manager</exception>
+        public static IManager RemoveManager<T>(this IDependencyManager depManager)
+        {
+            return depManager.RemoveManager(typeof(T));
+        }
+
+    }
+}