Revision 585292

AsyncLoop: replaces sharp clipping on a lower timeout value with a
smooth quadratic transition curve from an initial to a minimal timeout
value; updated documentation accordingly. Adjust actual timeout value
to timer resolution (ceiling) if Time::HiRes module is not available.

Conf+AsyncLoop: to a configuration variable rbl_timeout add two optional
parameters: a minimal timeout value, and a zone name if a timeout
specification should only apply to the specified zone or its subdomains;
update documentation accordingly.