Add extra createChannel options

Fixes #457. You know, some of these were introduced years ago, but this function has barely changed.

lib/Client.js

@@ -357,16 +357,32 @@ class Client extends EventEmitter {
     * @arg {String} name The name of the channel
     * @arg {String} [type=0] The type of the channel, either 0 (text), 2 (voice), or 4 (category)
     * @arg {String} [reason] The reason to be displayed in audit logs
-    * @arg {String} [parentID] ID of the parent category for a channel
+    * @arg {Object} [options] The properties the channel should have
+    * @arg {String} [options.topic] The topic of the channel (text channels only)
+    * @arg {Boolean} [options.nsfw] The nsfw status of the channel
+    * @arg {Number} [options.bitrate] The bitrate of the channel (voice channels only)
+    * @arg {Number} [options.userLimit] The channel user limit (voice channels only)
+    * @arg {Number} [options.rateLimitPerUser] The time in seconds a user has to wait before sending another message (does not affect bots or users with manageMessages/manageChannel permissions) (text channels only)
+    * @arg {String?} [options.parentID] The ID of the parent channel category for this channel
     * @returns {Promise<CategoryChannel | TextChannel | VoiceChannel>}
     */
-    createChannel(guildID, name, type, reason, parentID) {
+    createChannel(guildID, name, type, reason, options = {}) {
         const guild = this.guilds.get(guildID);
+        if(typeof options === "string") { // This used to be parentID, back-compat
+            options = {
+                parentID: options
+            };
+        }
         return this.requestHandler.request("POST", Endpoints.GUILD_CHANNELS(guildID), true, {
-            name,
-            type,
-            reason,
-            parent_id: parentID
+            name: name,
+            type: type,
+            reason: reason,
+            topic: options.topic,
+            nsfw: options.nsfw,
+            bitrate: options.bitrate,
+            user_limit: options.userLimit,
+            rate_limit_per_user: options.rateLimitPerUser,
+            parent_id: options.parentID
         }).then((channel) => {
             if(channel.type === 0) {
                 return new TextChannel(channel, guild);