New option to only allow registered users to speak WIP (#233):

* Prosody mod_muc_peertubelivechat_roles module
* Fix ConverseJS to disable the message field when room is unmoderated
  and user is visitor
* Mute/voice anonymous users when changing room configuration.
* Display a specific message to muted anonymous users.
* Default value for mute_anonymous in channel options.
* Feature documentation

conversejs/lib/plugins/livechat-specific.ts

@@ -9,7 +9,9 @@ export const livechatSpecificsPlugin = {
 
     _converse.api.settings.extend({
       // if user is authenticated with an external account (to add a logout button)
-      livechat_specific_external_authent: false
+      livechat_specific_external_authent: false,
+      // if user is anonymous
+      livechat_specific_is_anonymous: false
     })
 
     _converse.api.listen.on('getHeadingButtons', (view: any, buttons: any[]) => {