* Modified LogEntry to fit into the new logging mechanics
* Added commitRequests(), commitReferrers() and purgeReferrers() to Root prototype
* Added referrers collection to Root
* Re-added Site.spamfilter property for now
* Refactored Site.referrers_macro() and Story.referrers_macro() (formerly backlinks_macro, but compatibility is granted)
* Removed obsolete method Stories.flushRequests()
* Reactivated referrers (thus, including backlinks) for privileged users for testing purposes
* Added global nightly() method which is called from a new cronjob at 5 am
* Added calls for referrer purge and commit methods in Root to scheduler
* Added Story.count() method to increment the request counter; overwrites Helma's built-in HopObject method but it's anyway redundant with HopObject.size()
* Added utility methods for database access in Sql.js
