R1:5c5d3c35a780

Convert date-marker to ModularTransaction in Conpherence

Summary: Swaps this transaction over.

Test Plan: Load up a few rooms with date markers, still render as expected.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12550

Differential Revision: https://secure.phabricator.com/D17680