Fix Differential DashHeaders

Summary: Adds a basic style to ObjectItemList Headers. Fixes T5465

Test Plan: Added the same Query, tested various layouts

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T5465

Differential Revision: https://secure.phabricator.com/D9711
Add spacing under Pholio Inline Comments

Summary: Adds a bit of space

Test Plan: View 2 or more inline comments on same transaction.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9712
Disable Maniphest task list grips in panel rendering contexts

Summary:
Fixes T5467.

  - Let search engines figure out if they're rendering for a panel or not.
  - If Maniphest is rendering a panel, turn off the grips and batch selection.

Test Plan:
  - Viewed task panels (no grips).
  - Viewed non-panel query results (grips).

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T5467

Differential Revision: https://secure.phabricator.com/D9714
Let PHUITagView colorize completely with "shades"

Summary: See D9710.

Test Plan: quack quack

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D9713
mailgun support messageids. supportsMessageIDHeader accidentally returned false.

Summary: The adapter was mostly copy-paste, and I missed the supportsMessageIDHeader stuff.

Test Plan: Sent a message, checked headers.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9715
Improve out-of-the-box compatability with Mail.app's threading

Summary:
Mail.app is a little touchy about how it does threading.
If your mail adapter supports the Message-ID email header AND follow-up messages are prefixed with "Re: ",
it will correctly thread messages together.

This change changes the behavior of subject consturction:
- when metamta.re-prefix is false, Phabricator will prefix "Re: " to follow up messages ONLY, which seems like the sensible thing to do in most cases. This has no negative side-effects as far as I can tell, and it makes
Mail.app "just work" if your adapter supports Message-IDs.
- when metamta.re-prefix is true, it retains the previous behavior of prefixing "Re: " to all messages, including the first one. This is a hack that's only required when your adapter doesn't support Message-IDs (like Amazon SNS & SendGrid. Is this still the case?)

metamta.re-prefix probably needs to be renamed to something else (metamta.force-re-prefix ?) and have a migration script added.

Test Plan: Tested on Gmail and Mail.app, with various combinations (metamta.can-send-as-user turned on and off). Threading now just works, and the topics aren't uglified by it (since the first message is not prefixed with "Re: ")

Reviewers: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9716
Merge branch 'upstream/master'
Merge branch 'improved_mail.app_support'