Session management system

- Managers bound to the session instead of to Torch
- TorchSession automatic creation and destruction
- Automatic manager creation for sessions

Torch.API/Session/ITorchSession.cs

@@ -0,0 +1,29 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Sandbox.Game.World;
+using Torch.API.Managers;
+
+namespace Torch.API.Session
+{
+    /// <summary>
+    /// Represents the Torch code working with a single game session
+    /// </summary>
+    public interface ITorchSession
+    {
+        /// <summary>
+        /// The Torch instance this session is bound to
+        /// </summary>
+        ITorchBase Torch { get; }
+
+        /// <summary>
+        /// The Space Engineers game session this session is bound to.
+        /// </summary>
+        MySession KeenSession { get; }
+
+        /// <inheritdoc cref="IDependencyManager"/>
+        IDependencyManager Managers { get; }
+    }
+}