[improvement] : moderate and custom registration
Currently, registration on Mobilizon is either open or closed. But there are many good reasons to have something more sophisticated: restricting registrations to one or more domains, personalized account creation invitation by email, invitation on secret link (as mastodon allows), captcha... Currently, if we open the registrations, we are especially prey to spammers who create accounts and flood us with fraudulent events. How to allow our users to register, without having to deal with this volume of spam ?