Rate limiting was already redesigned to use Python limits. This
introduced some unexpected behavior, including the fact that only
one criteria is supported per limiter. Docs and setup utility are
updated with this in mind.
Also, the code was made more generic, so limiters can be delivered
for something else than authentication. Authentication-specific
code was moved directly to the authentication routine.
This will make network configuration and host based authentication
more robust, across different deployment platforms.
The options `RELAYNETS` and`POD_ADDRESS_RANGE` are kept for compatibility.
However, their usage have become optional.
To facilitate this, the default redirect at / can be disabled, even if
the default remains at redirecting to the webmailer.
The extensions are within the host scope and are read from
$ROOT/overrides/nginx/*.conf.
kaiyou