Implemented command type readers, parser and service.

src/Discord.Net.Commands/CommandParameter.cs

@@ -0,0 +1,34 @@
+using System.Diagnostics;
+using System.Threading.Tasks;
+
+namespace Discord.Commands
+{
+    //TODO: Add support for Multiple
+    [DebuggerDisplay(@"{DebuggerDisplay,nq}")]
+    public class CommandParameter
+    {
+        private readonly TypeReader _reader;
+
+        public string Name { get; }
+        public string Description { get; }
+        public bool IsOptional { get; }
+        public bool IsUnparsed { get; }
+        internal object DefaultValue { get; }
+
+        public CommandParameter(string name, string description, TypeReader reader, bool isOptional, bool isUnparsed, object defaultValue)
+        {
+            _reader = reader;
+            IsOptional = isOptional;
+            IsUnparsed = isUnparsed;
+            DefaultValue = defaultValue;
+        }
+
+        public async Task<TypeReaderResult> Parse(IMessage context, string input)
+        {
+            return await _reader.Read(context, input).ConfigureAwait(false);
+        }
+
+        public override string ToString() => Name;
+        private string DebuggerDisplay => $"{Name}{(IsOptional ? " (Optional)" : "")}{(IsUnparsed ? " (Unparsed)" : "")}";
+    }
+}