don't throw BadMethodCallException on diffs that add images

Summary:
I don't know if there is something more sinister going on
under the covers, but we have a couple of diffs that trigger:

Unhandled Exception ("BadMethodCallException")
Call to a member function getMetadata() on a non-object

when the diff page is handling its async render calls.  One diff
in particular has multiple image adds and thus has a stack of of these
error dialogs to close.

This isn't a new regression, we just haven't gotten around to debugging
it until now (reported on 6/12)

One revision that triggers it has two diffs.  If I show Base -> Diff 1
I don't hit the error.  When I select Base -> Diff 2, or Diff 1 -> Diff
2, the error triggers.

I don't understand what this means, but this diff avoids the null object
reference that causes the exception.

Test Plan:
Load the offending diff, don't hit the error. The diff loads
the images that were added

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, aran

Differential Revision: https://secure.phabricator.com/D6851
Allow MetaMTA adapters to indicate that a mail is permanently undeliverable

Summary: Currently, adapters can only fail mail temporarily. Allow them to indicate a permanent failure by throwing a special exception.

Test Plan: Added and ran unit tests.

Reviewers: wez, btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D6847
Compose and display method information in Diviner

Summary:
Ref T988. As mentioned elsewhere, one broad goal of this iteration is to reduce the amount of boilerplate documentation we need to write. For example:

  - I want to set `@group` by default in most cases.
  - I want to inherit things like `@param` and `@return` by default.
  - I want to inherit method documentation by default.
  - I want to inherit `@task` information.

This implements most of the method inheritance stuff.

This //looks// super gross, but I believe we now compose all of the information of interest at display time and can work on rendering it sensibly in the near future.

Test Plan: {F56790}

Reviewers: btrahan, chad

Reviewed By: btrahan

CC: aran, sascha-egerer

Maniphest Tasks: T988

Differential Revision: https://secure.phabricator.com/D6849
In Diviner, parse "abstract" and "final" in PHP classes, interfaces and methods

Summary: Ref T988. Adds support for the "abstract" and "final" keywords in the atomizer.

Test Plan: Looked at abstract/final stuff.

Reviewers: btrahan, chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T988

Differential Revision: https://secure.phabricator.com/D6850
Restore white background to Paste

Summary: I think we lost this recently (maybe with the line highlighting change), but it's more readable if we put these on a white background.

Test Plan: Looked at a Paste (like `/P123`), saw white background.

Reviewers: chad, btrahan, asherkin

Reviewed By: asherkin

CC: aran

Differential Revision: https://secure.phabricator.com/D6852
Add Base Grey set of colors

Summary: This adds a set of standard grey colors for use in shading objects and importance. I'll follow up and start implementing in another diff.

Test Plan: Color UI Examples, Adobe Kuler

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: Korvin, aran

Differential Revision: https://secure.phabricator.com/D6853