Fatal during setup for "mbstring.func_overload"

Summary:
Fixes T5545. We assume `strlen()` returns the number of bytes in a string, which is the normal behavior (and the documented behavior).

There's a config option, `mbstring.func_overload`, which silently calls mb_strlen() instead. This may return some other result, might fail, etc., and there's no way to get the byte length of a string if this option is set.

If this option is set, fatal immediately. Nothing good can ever come of it.

Test Plan: {F173990}

Reviewers: btrahan, chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T5545

Differential Revision: https://secure.phabricator.com/D9811
Allow Legalpad documents to designate corporate signers

Summary:
Ref T5532. This adds:

  - Documents can designate that they should be signed by "Corporations" or "Individuals".
  - Corporate documents get different fields and a different exemption process.
  - Basically everything works the same but this is like a zillion lines of form code.

Test Plan: See screenshots.

Reviewers: btrahan, chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T5532

Differential Revision: https://secure.phabricator.com/D9812
Allow users to specify names of build steps

Summary: Ref T1049.  This provides a user-configurable name field on build steps, which allows users to uniquely identify their steps.  The intention is that this field will be used in D9806 to better identify the dependencies (rather than showing an unhelpful PHID).

Test Plan: Set the name of some build steps, saw it appear in the correct places.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Maniphest Tasks: T1049

Differential Revision: https://secure.phabricator.com/D9816
Add an optional preamble to Legalpad documents

Summary:
Fixes T5532. Allow documents to have a preamble in the header which can be used to explain who should sign a document and why.

Particularly, I plan to use this to navigate the corporate vs individual stuff more sensibly.

Test Plan: {F174228}

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T5532

Differential Revision: https://secure.phabricator.com/D9819
Point contributor documentation at Phacility CLAs, not Facebook CLAs

Summary: We now have workable CLAs, so route users to them.

Test Plan: Read documentation.

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D9820
Improve the `PhabricatorInfrastructureTestCase` unit tests

Summary:
Improve the `PhabricatorInfrastructureTestCase` unit tests such that they will fail if any of the following conditions are satisfied:

- A symbol referenced in the `__phutil_library_map__.php` file no longer exists.
- A symbol exists in the library but is not referenced within the `__phutil_library_map__.php` file.
- A symbol extends from a different parent symbol than that declared in the `__phutil_library_map.php` file.

Test Plan: See D9824.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9827
Minor, don't link commits after a semicolon

Summary: This stops us from trying to capture commit refs in Diffusion URIs.

Auditors: btrahan
Show project hashtags prominently on project pages

Summary: Currently, it's unreasonably difficult for users to figure out some project hashtags because the rules aren't always intuitive.

Test Plan: {F174508}

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D9830
Render hashtags as colored/icon'd project tags

Summary: In most cases we preserve what the user typed, but showing colors/icons/names is more useful than `#yolo` (and makes aliases more usable without loss of meaning).

Test Plan: {F174510}

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D9831
In Phabricator, disregard src/extensions for unit tests

Summary: See D9834. Phabricator flavor.

Test Plan: See D9834.

Reviewers: joshuaspence

Reviewed By: joshuaspence

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D9836
Minor change to `PhabricatorInfrastructureTestCase::testLibraryMap`

Summary: Modify `PhabricatorInfrastructureTestCase::testLibraryMap` to use `phutil_get_current_library_name()` instead of hard-coding the library name.

Test Plan: See D9844.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9845
Fix typo in ConfigWelcomeController support text

See: <https://github.com/phacility/phabricator/pull/670>

Reviewed by: epriestley
Merge branch 'master' of github.com:facebook/phabricator