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/Network/Packets/OutgoingAccountPackets.cs

@@ -374,7 +374,7 @@ namespace Server.Network
                     writer.Write(ci.X);
                     writer.Write(ci.Y);
                     writer.Write(ci.Z);
-                    writer.Write(ci.Map.MapID);
+                    writer.Write(ci.Map?.MapID ?? 0);
                     writer.Write(ci.Description);
                     writer.Write(0);
                 }