Updates Serialization (#292)

- [X] Removes all save strategies
- [X] Removes duplicate file writer that won't be used
- [X] Removes persistence (it will become a duplicate system)
- [X] Add a save position variable to skip serializing a clean item/mobile
- [X] Update Guilds/Accounts to be IEntity types
    - Because guilds are abstract, this may make serialization tricky.
- [X] Update the generalized IEntity writing
- [X] Update the load/save to write to buffers then to files in background


Bumps release version

Projects/Server/World/EntityIndex.cs

@@ -0,0 +1,36 @@
+/*************************************************************************
+ * ModernUO                                                              *
+ * Copyright 2019-2020 - ModernUO Development Team                       *
+ * Email: hi@modernuo.com                                                *
+ * File: EntityIndex.cs                                                  *
+ *                                                                       *
+ * This program is free software: you can redistribute it and/or modify  *
+ * it under the terms of the GNU General Public License as published by  *
+ * the Free Software Foundation, either version 3 of the License, or     *
+ * (at your option) any later version.                                   *
+ *                                                                       *
+ * You should have received a copy of the GNU General Public License     *
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+namespace Server
+{
+    public readonly struct EntityIndex<T> where T : ISerializable
+    {
+        public T Entity { get; }
+
+        public int TypeID { get;  }
+
+        public long Position { get; }
+
+        public int Length { get; }
+
+        public EntityIndex(T entity, int typeID, long position, int length)
+        {
+            Entity = entity;
+            TypeID = typeID;
+            Position = position;
+            Length = length;
+        }
+    }
+}