With the previous 10 minutes / minute limit we were still hitting
Telegram API rate limit (the 429, "Too Many Requests" response)
from time to time.

Therefore, tighten the limit a bit on our side.

The PhoneNumberForm is used in "Add SMS" and "Add Phone Call" pages.
The PhoneUpDownForm is a subclass of PhoneNumberForm and
adds "up" and "down" boolean fields. It is used in "Add Signal"
and "Add WhatsApp" pages.

Fixes: #428

Fixes: #465

Need it to escape quirks mode in email clients.

Fixes: #347

Not using them anywhere on the site currently, so commented them out
in bootstrap.less and regenerated bootstrap.css.

Fix simple typo in docs, libary -> library

There is a small typo in templates/docs/python.md.

Should read `library` rather than `libary`.

Fixes: #348

Fixes: #462

Fixes: #450

* Add HTTP header authentiation backend/middleware

* Add docs for remote header auth

* Improve docs on external auth

* Add warning for unknown  REMOTE_USER_HEADER_TYPE

* Move active check for header auth to middleware
Add extra header type sanity check to the backend

* Add test cases for remote header login

* Improve header-based authentication

- remove the 'ID' mode
- add CustomHeaderBackend to AUTHENTICATION_BACKENDS conditionally
- rewrite CustomHeaderBackend and CustomHeaderMiddleware to
use less inherited code
- add more test cases

Co-authored-by: Pēteris Caune <[email protected]>

Move terraform-provider-healthchecksio to the "API Wrappers"
category, which is more appropriate than "Tools for Self-Hosting".

Move terraform-provider-healthchecksio to the "API Wrappers"
category, which is more appropriate than "Tools for Self-Hosting".

Fixes #455

Fixes #282

User handle is used in a username-less authentication, to map a
credential received from browser with an user account in the
database. Since we only use security keys as a second factor,
the user handle is not of much use to us.

The user handle:
 - must not be blank,
 - must not be a constant value,
 - must not contain personally identifiable information.

So we use random bytes, and don't store them on our end.