Split development-only classes into a new sub-project in devel/. This
sub-project is used only for development and is never deployed to artifact repositories.
Updated dependencies.
Removed DNSBL for dnsbl.openresolvers.org, which no longer exists and is now just a
domain-for-sale page.
Updated list of DNSBL lookups to match current sources.
Changed DNS query timeout from 5 seconds to 30 seconds.