feat(spawners): Adds Respawn, EditSpawner, and SpawnProps commands (#532)

- [X] Adds `Respawn` command
- [X] Adds `EditSpawner` command
  - Usage: `[global editspawner <type> <arguments> set <properties>`
  - This command replaces the arguments (optional) and properties of the affected spawners for that type
- [X] Adds `SpawnProps` command
  - Usage: `[area spawnprops`
  - This command brings up a gump to modify targeted spawners based on the targeted entity.
  - To do this, the props/values are copied and then used to construct a properties list for the spawner entry.

Closes #531

Projects/UOContent/Engines/Spawners/SpawnPropsGumpCommand.cs

@@ -0,0 +1,73 @@
+/*************************************************************************
+ * ModernUO                                                              *
+ * Copyright (C) 2019-2021 - ModernUO Development Team                   *
+ * Email: hi@modernuo.com                                                *
+ * File: SpawnPropsGump.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/>. *
+ *************************************************************************/
+
+using System.Collections.Generic;
+using Server.Commands;
+using Server.Commands.Generic;
+using Server.Gumps;
+using Server.Targeting;
+
+namespace Server.Engines.Spawners
+{
+    public class SpawnPropsGumpCommand : BaseCommand
+    {
+        public static void Initialize()
+        {
+            TargetCommands.Register(new SpawnPropsGumpCommand());
+        }
+
+        public SpawnPropsGumpCommand()
+        {
+            AccessLevel = AccessLevel.GameMaster;
+            Supports = CommandSupport.Complex | CommandSupport.Simple;
+            Commands = new[] { "SpawnProps" };
+            ObjectTypes = ObjectTypes.Items;
+            Usage = "SpawnProps";
+            Description = "Shows a props gump that will modify the properties of spawn entries related to the chosen entity";
+            ListOptimized = true;
+        }
+
+        public override void ExecuteList(CommandEventArgs e, List<object> list)
+        {
+            if (list.Count == 0)
+            {
+                LogFailure("No matching objects found.");
+                return;
+            }
+
+            e.Mobile.SendMessage("Target the object you want to use as a template for modifying the spawner properties.");
+            e.Mobile.Target = new InternalTarget(list);
+        }
+
+        private class InternalTarget : Target
+        {
+            private List<object> _list;
+
+            public InternalTarget(List<object> list) : base(-1, false, TargetFlags.None) =>
+                _list = list;
+
+            protected override void OnTarget(Mobile from, object targeted)
+            {
+                var type = targeted.GetType();
+                if (!Add.IsEntity(type))
+                {
+                    from.SendMessage("No type with that name was found.");
+                }
+
+                from.SendGump(new SpawnPropsGump(from, targeted, _list));
+            }
+        }
+    }
+}