fix(core): Updates expansion and map configurations (fixes map issues) (#570)

- [X] Adds question about expansion at start of server
- [X] Adds question about client version to determine old have and map diffs
- [X] Adds config setting "maps.enablePre6000Trammel"
- [X] Rearranges some of the loading order.
- [X] Added support for deserializing nullable enums from json

TODO:
Expand the nullable enums deserialization factory to work with any type by pulling the factory and creating an instance of the converter.

Projects/Server/Items/VirtualCheck.cs

@@ -20,8 +20,12 @@ namespace Server.Items
 {
     public sealed class VirtualCheck : Item
     {
-        // TODO: Move to configuration
-        public static bool UseEditGump = false;
+        public static bool UseEditGump { get; private set; }
+
+        public static void Configure()
+        {
+            UseEditGump = ServerConfiguration.GetSetting("virtualChecks.useEditGump", true);
+        }
 
         private int m_Gold;