Missing email address check

[gabriel-BW]

On signup there is a check about the email address (checking if it's already used, and sending a confirmation link to check if it's yours). But when you change it on your profile, there is no check at all... It would be appropriate to add the same checks, even if it means being logged out until a new mail confirmation is performed. If necessary, changing the email address could be moved out of the profile (in the same way as changing the password).
I'm bringing this up now, because we had a complaint from someone who claimed an account had been created in her name with real data (photo, etc) about her and her email address, but she didn't create it herself. And that's actually possible, if someone created the account with their own email and then changed it to hers. So she was unexpectedly receiving hosting requests... This can be done as a bad joke, or as revenge from an ex-lover or something similar.