* Password reset
* Various improvements and fixes for password reset
- Reorganize src/mail.rs to make it cleaner
- add a build_mail function
- only make the requests invalid after 2 hours
- avoid infintely-growing list of requests by deleting them once completed, or after 24 hours
- avoid sending many requests for the same user
- validate the password reset form
* Avoid locking so many times
Fix durations
* Remove old requests even if the current one is not valid
* Remove unused feature
* Also remove the custom_derive and plugin features while we are at it
* Forgot a 0 è_é
* Avoid panicking while owning a request lock
* Use master branch of lettre so that we can build with the latest OpenSSL
* Fix the debug mailer
