Start work on command builders

Right now commands require a module before they can be created;
I'm looking to remove this in the future.

src/Discord.Net.Commands/Builders/CommandBuilder.cs

@@ -0,0 +1,69 @@
+using System;
+using System.Threading.Tasks;
+using System.Collections.Generic;
+
+namespace Discord.Commands
+{
+    public class CommandBuilder
+    {
+        private List<string> aliases;
+
+        internal CommandBuilder(ModuleBuilder module, string prefix)
+        {
+            aliases = new List<string>();
+
+            if (prefix != null)
+            {
+                aliases.Add(prefix);
+                Name = prefix;
+            }
+
+            Module = module;
+        }
+
+
+        public string Name { get; set; }
+        public string Summary { get; set; }
+        public string Remarks { get; set; }
+        public Func<object[], Task> Callback { get; set; }
+        public ModuleBuilder Module { get; }
+
+        public List<string> Aliases => aliases;
+
+
+        public CommandBuilder SetName(string name)
+        {
+            Name = name;
+            return this;
+        }
+
+        public CommandBuilder SetSummary(string summary)
+        {
+            Summary = summary;
+            return this;
+        }
+
+        public CommandBuilder SetRemarks(string remarks)
+        {
+            Remarks = remarks;
+            return this;
+        }
+
+        public CommandBuilder SetCallback(Func<object[], Task> callback)
+        {
+            Callback = callback;
+            return this;
+        }
+
+        public CommandBuilder AddAlias(string alias)
+        {
+            aliases.Add(alias);
+            return this;
+        }
+
+        public ModuleBuilder Done()
+        {
+            return Module;
+        }
+    }
+}

src/Discord.Net.Commands/Builders/ModuleBuilder.cs

@@ -0,0 +1,102 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+
+namespace Discord.Commands
+{
+    public class ModuleBuilder
+    {
+        private List<CommandBuilder> commands;
+        private List<ModuleBuilder> submodules;
+        private List<string> aliases;
+
+
+        public ModuleBuilder()
+            : this(null, null)
+        { }
+
+        public ModuleBuilder(string prefix)
+            : this(null, prefix)
+        { }
+
+        internal ModuleBuilder(ModuleBuilder parent)
+            : this(parent, null)
+        { }
+
+        internal ModuleBuilder(ModuleBuilder parent, string prefix)
+        {
+            commands = new List<CommandBuilder>();
+            submodules = new List<ModuleBuilder>();
+            aliases = new List<string>();
+
+            if (prefix != null)
+            {
+                aliases.Add(prefix);
+                Name = prefix;
+            }
+            
+            ParentModule = parent;
+        }
+
+
+        public string Name { get; set; }
+        public string Summary { get; set; }
+        public string Remarks { get; set; }
+        public ModuleBuilder ParentModule { get; }
+
+        public List<CommandBuilder> Commands => commands;
+        public List<ModuleBuilder> Modules => submodules;
+        public List<string> Aliases => aliases;
+
+
+        public ModuleBuilder SetName(string name)
+        {
+            Name = name;
+            return this;
+        }
+
+        public ModuleBuilder SetSummary(string summary)
+        {
+            Summary = summary;
+            return this;
+        }
+
+        public ModuleBuilder SetRemarks(string remarks)
+        {
+            Remarks = remarks;
+            return this;
+        }
+
+        public ModuleBuilder AddAlias(string alias)
+        {
+            aliases.Add(alias);
+            return this;
+        }
+
+        public CommandBuilder AddCommand() => AddCommand(null);
+        public CommandBuilder AddCommand(string name)
+        {
+            var builder = new CommandBuilder(this, name);
+            commands.Add(builder);
+
+            return builder;
+        }
+
+        public ModuleBuilder AddSubmodule() => AddSubmodule(null);
+        public ModuleBuilder AddSubmodule(string prefix)
+        {
+            var builder = new ModuleBuilder(this, prefix);
+            submodules.Add(builder);
+
+            return builder;
+        }
+
+        public ModuleBuilder Done()
+        {
+            if (ParentModule == null)
+                throw new InvalidOperationException("Cannot finish a top-level module!");
+
+            return ParentModule;
+        }
+    }
+}