Password reset (#448)

* 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

templates/session/password_reset_request_ok.rs.html

@@ -0,0 +1,9 @@
+@use template_utils::*;
+@use templates::base;
+
+@(ctx: BaseContext)
+
+@:base(ctx, i18n!(ctx.1, "Password reset"), {}, {}, {
+  <h1>@i18n!(ctx.1, "Check your inbox!")</h1>
+  <p>@i18n!(ctx.1, "We sent a mail to the address you gave us, with a link to reset your password.")</p>
+})