Mailster v2.3.11
* fixed: added "source" tag in allowed tags
* fixed: sql query issue on '(didn't) clicked link' condition
* fixed: smaller issues
* fixed: unsubscribe issue on single opt out if user is logged in
* fixed: subscriber export on sites with CloudFlare
* improved: custom tags are now replaced in the final campaign and no longer when created
* improved: privacy policy link gets updated if the address changes
* improved: subscriber query now has the campaign id as second argument.
* improved: nonce form handle
* added: `wp_include` and `wp_exclude` for subscriber query to handle WP user ID's
* added: condition '(didn't) clicked link' now allows to choose a certain campaign
* added: additional aggregated campaigns