* For anonymous users: new "log in using an external account" dialog, with the "remote Peertube account" options
* ConverseJS: using global vars for custom localized string (injected
using Webpack)
Hide nickname changes when previous nickname was like "Anonymous 12345".
Helps to improve performances when massive anonymous users are joining (#138), and prevent displaying unnecessary messages (#111).
* if both local and remote instance have external XMPP connections enabled, the user joins the remote room with his local account
* some code refactoring (builtin.ts)
Note: documentation and settings descriptions are to do.
Related to #112