R1:e15009b76e1b

Show "reply" inlines as replies in the objective list

Summary: Ref T12733. Show a "reply" icon for replies, and make them stack directly under their parent.

Test Plan: {F4968500}

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12733

Differential Revision: https://secure.phabricator.com/D17981