Remove collection of emails for self-registered users

[vmcj]

In all years that I've worked with DOMjudge I've never seen a good reason to collect the email separately. So I propose to remove the collection in the next major release.

We keep storing the emails in development dumps and although it doesn´t hurt that much it is a bit more privacy sensitive than most other fields IMHO.

[Kevinjil]

This is one of those features I have no idea if anyone in the world is using it. I can imagine use cases when self-signup enabled and, e.g. after contest, you'd like to sent out mail to whoever entered an email address.

[meisterT]

Is entering an email address mandatory right now? If so, could me make it optional instead of dropping it?

There might be installations out there which suddenly lose data that may be important to them (because that's how they can communicate with their users).

[vmcj]

Is entering an email address mandatory right now? If so, could me make it optional instead of dropping it?

It's already optional, we still get them in our dumps as it's implied with such installation that you might get an confirmation email?

There might be installations out there which suddenly lose data that may be important to them (because that's how they can communicate with their users).

In the 2nd commit we don't drop the column if it exists, only on new installs the column is not created. That is the intent at least.