Add new `NUMBER` option type (https://discord.com/developers/docs/int… (#60)

* Add new `NUMBER` option type (https://discord.com/developers/docs/interactions/slash-commands#application-command-object-application-command-option-type)

https://discord.com/developers/docs/interactions/slash-commands#application-command-object-application-command-option-type

* Add number to SocketSlashCommandDataOption.cs

src/Discord.Net.Core/Entities/Interactions/ApplicationCommandOptionType.cs

@@ -54,6 +54,11 @@ namespace Discord
         /// <summary>
         ///     A <see cref="IUser"/> or <see cref="IRole"/>.
         /// </summary>
-        Mentionable = 9
+        Mentionable = 9,
+        
+        /// <summary>
+        ///     A <see cref="double"/>.
+        /// </summary>
+        Number = 10
     }
 }

src/Discord.Net.WebSocket/Entities/Interaction/Slash Commands/SocketSlashCommandDataOption.cs

@@ -96,7 +96,15 @@ namespace Discord.WebSocket
                         {
                             if (model.Value.Value is bool val)
                                 this.Value = val;
-                            else if (bool.TryParse(model.Value.Value.ToString(), out var res))
+                            else if (bool.TryParse(model.Value.Value.ToString(), out bool res))
+                                this.Value = res;
+                        }
+                        break;
+                    case ApplicationCommandOptionType.Number:
+                        {
+                            if (model.Value.Value is int val)
+                                this.Value = val;
+                            else if (double.TryParse(model.Value.Value.ToString(), out double res))
                                 this.Value = res;
                         }
                         break;