Feature: Digests (automated newsletters)
Feature: Digest Log
Feature: Ability to set the default frequency for the Digest
Feature: Digests can now be set to Daily
Feature: Keywords can now be optionally restricted to only appear for certain Mailing Lists
Change: The Digest cron job now prioritises users who have not received the Digest for a while, rather than prioritising the lowest User ID
Change: The web view of an email will now handle replacement variables
Change: Inactive mailing lists will no longer show up in maintenance actions
Fix: Keyword data was not unserialised correctly, leading to PHP errors on Keyword Subscription and Send Mail