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/EditSpawnCommand.cs

@@ -0,0 +1,113 @@
+/*************************************************************************
+ * ModernUO                                                              *
+ * Copyright (C) 2019-2021 - ModernUO Development Team                   *
+ * Email: hi@modernuo.com                                                *
+ * File: EditSpawnCommand.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;
+using System.Collections.Generic;
+using Server.Commands;
+using Server.Commands.Generic;
+using Server.Network;
+
+namespace Server.Engines.Spawners
+{
+    public class EditSpawnCommand : BaseCommand
+    {
+        public static void Initialize()
+        {
+            TargetCommands.Register(new EditSpawnCommand());
+        }
+
+        public EditSpawnCommand()
+        {
+            AccessLevel = AccessLevel.GameMaster;
+            Supports = CommandSupport.Complex | CommandSupport.Simple;
+            Commands = new[] { "EditSpawner" };
+            ObjectTypes = ObjectTypes.Items;
+            Usage = "EditSpawner <type> <arguments> set <properties>";
+            Description = "Modifies spawners arguments and properties for the given type";
+            ListOptimized = true;
+        }
+
+        public override void ExecuteList(CommandEventArgs e, List<object> list)
+        {
+            var args = e.Arguments;
+
+            if (args.Length <= 1)
+            {
+                LogFailure(Usage);
+                return;
+            }
+
+            if (list.Count == 0)
+            {
+                LogFailure("No matching objects found.");
+                return;
+            }
+
+            var name = args[0];
+
+            var type = AssemblyHandler.FindTypeByName(name);
+
+            if (!Add.IsEntity(type))
+            {
+                LogFailure("No type with that name was found.");
+                return;
+            }
+
+            var argSpan = e.ArgString.AsSpan(name.Length + 1);
+            var setIndex = argSpan.InsensitiveIndexOf("set ");
+
+            ReadOnlySpan<char> props = null;
+
+            if (setIndex > -1)
+            {
+                var start = setIndex + 4;
+                props = argSpan.Slice(start, argSpan.Length - start);
+                argSpan = argSpan.SliceToLength(setIndex);
+            }
+
+            var argStr = argSpan.ToString().DefaultIfNullOrEmpty(null);
+            var propsStr = props.ToString().DefaultIfNullOrEmpty(null);
+
+            e.Mobile.SendMessage("Updating spawners...");
+
+            foreach (var obj in list)
+            {
+                if (obj is BaseSpawner spawner)
+                {
+                    UpdateSpawner(spawner, name, argStr, propsStr);
+                }
+            }
+
+            e.Mobile.SendMessage("Update completed.");
+        }
+
+        public static void UpdateSpawner(BaseSpawner spawner, string name, string arguments, string properties)
+        {
+            foreach (var entry in spawner.Entries)
+            {
+                // TODO: Should cache spawn type on the entry
+                if (entry.SpawnedName.InsensitiveEquals(name))
+                {
+                    if (arguments != null)
+                    {
+                        entry.Parameters = arguments;
+                    }
+
+                    entry.Properties = properties;
+                }
+            }
+        }
+    }
+}