Simplify registration flow

[kontrollanten]

Describe the problem to be solved

Currently users has to provide public name and username during registration, which may be confusing and an obstacle for users whom just want to register to subscribe to a channel.

Describe the solution you would like

1. Hide the public name field during registration and make it optional to provide after registration.
2. Give an example where public name are shown; This is the name that will be publicly visible by other users, e.g. when publishing comments..
3. Simplify description of the username: This is name will be displayed in your public profile..
4. Remove the instance URL after the username (@instance-domain.com) since it may give users the impression that they'll create an email address.
5. Automatically fill the username based on the email address. If the username is already taken, add numbers after the username:

[vencabot]

I think these are all fantastic ideas. Wow! Good thinking.