Target contacts based on engagement with a previous CiviMail blast

Scenario: A CiviMail user has sent one mail blast and seeks to follow-up with recipients, perhaps scheduling a phone call or sending a second mailing. In targeting the second interaction, the user wishes to differentiate constituents based on whether they received, opened, clicked-through, or replied to the initial mailing.

Approach: Implement an "Advanced Search" panel for CiviMail which can filter based on mailing events.

See attached patch. Note that the patch doesn't manipulate a couple bits of key metadata:

• Add option value in group "advanced_search_options" with name "CiviMail" and label "Mailings"
• Enable CiviMail in the "civicrm_preferences" named "advanced_search_options"