Cleaned up a few internal command constructor, fixed subgroups not maintaining category

src/Discord.Net.Commands/CommandBuilder.cs

@@ -121,10 +121,11 @@ namespace Discord.Commands
 
 		public CommandService Service => _service;
 
-		internal CommandGroupBuilder(CommandService service, string prefix, IEnumerable<IPermissionChecker> initialChecks = null)
+		internal CommandGroupBuilder(CommandService service, string prefix = "", string category = null, IEnumerable<IPermissionChecker> initialChecks = null)
 		{
 			_service = service;
 			_prefix = prefix;
+            _category = category;
 			if (initialChecks != null)
 				_checks = new List<IPermissionChecker>(initialChecks);
 			else
@@ -145,9 +146,9 @@ namespace Discord.Commands
 			_checks.Add(new GenericPermissionChecker(checkFunc, errorMsg));
 		}
 
-		public CommandGroupBuilder CreateGroup(string cmd, Action<CommandGroupBuilder> config = null)
-		{			
-			config(new CommandGroupBuilder(_service, CommandBuilder.AppendPrefix(_prefix, cmd), _checks));
+		public CommandGroupBuilder CreateGroup(string cmd, Action<CommandGroupBuilder> config)
+		{
+            config(new CommandGroupBuilder(_service, CommandBuilder.AppendPrefix(_prefix, cmd), _category, _checks));
 			return this;
 		}
 		public CommandBuilder CreateCommand()

src/Discord.Net.Commands/CommandMap.cs

@@ -20,16 +20,20 @@ namespace Discord.Commands
 		public IEnumerable<Command> Commands => _commands;
 		public IEnumerable<CommandMap> SubGroups => _items.Values;
 
-		public CommandMap(CommandMap parent, string name, string fullName)
+        public CommandMap()
+        {
+            _items = new Dictionary<string, CommandMap>();
+            _commands = new List<Command>();
+            _isVisible = false;
+            _hasNonAliases = false;
+            _hasSubGroups = false;
+        }
+        public CommandMap(CommandMap parent, string name, string fullName)
+            : this()
 		{
 			_parent = parent;
 			_name = name;
 			_fullName = fullName;
-            _items = new Dictionary<string, CommandMap>();
-			_commands = new List<Command>();
-			_isVisible = false;
-			_hasNonAliases = false;
-			_hasSubGroups = false;
         }
 		
 		public CommandMap GetItem(string text)

src/Discord.Net.Commands/CommandService.cs

@@ -34,9 +34,9 @@ namespace Discord.Commands
             Config = config;
 
 			_allCommands = new List<Command>();
-			_map = new CommandMap(null, "", "");
+			_map = new CommandMap();
 			_categories = new Dictionary<string, CommandMap>();
-            Root = new CommandGroupBuilder(this, "", null);
+            Root = new CommandGroupBuilder(this);
 		}
 
 		void IService.Install(DiscordClient client)
@@ -309,7 +309,7 @@ namespace Discord.Commands
             string categoryName = command.Category ?? "";
 			if (!_categories.TryGetValue(categoryName, out category))
 			{
-				category = new CommandMap(null, "", "");
+				category = new CommandMap();
 				_categories.Add(categoryName, category);
 			}