Lint for PHP 5.3 on Windows

Test Plan: Linted `FileFinder`.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5972
Implementing prefix and suffix diffing for multi-byte unicode characters.

Summary: Prefix and suffix diffing for multi-byte unicode characters.

Test Plan:
Test diff:
------------------------------------------------------------
diff --git a/test b/test
index 252ad2f..a5bad3b 100644
--- a/test
+++ b/test
@@ -1 +1 @@
-This file contains this and this stuff.
+This file contains žžžž and this stuff.
--------------------------------------------------------------

{F43738}
--------------------------------------------------------------

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin, AnhNhan

Maniphest Tasks: T2379

Differential Revision: https://secure.phabricator.com/D5925
Update PHP compat info

Summary: Also warn against functions not available on Windows at all.

Test Plan: Compared old and new file.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5975
Allow an unassigned flag to be passed to `arc tasks`

Summary: Returns unassigned tasks

Test Plan: Run `arc tasks`, `arc tasks --unassigned`, make sure I get the correct results

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T3201

Differential Revision: https://secure.phabricator.com/D6009
Use PhutilEditDistanceMatrix in ArcanistDiffUtils

Summary: Replace this old hard-coded implementation with the new vector-based, unicode-capable one.

Test Plan: Ran unit tests. Looked at revisions in Differential, using whitespace modes to bypass cache.

Reviewers: btrahan, Afaque_Hussain

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2379

Differential Revision: https://secure.phabricator.com/D6016
Compute UTF8 string differences correctly, accounting for combining characters

Summary:
@Afaque_Hussain has done a bunch of utf8 work here; combined with PhutilEditDistanceMatrix we can now do utf8 diffs correctly, in a general way, without a significant performance impact.

Use PhutilEditDistanceMatrix and `phutil_utf8v_combined()` to compute accurate diffs for all (or, at least, most) UTF8 text.

The only thing this doesn't handle completely correctly is lines beginning with combining characters. This is messy/expensive to handle and will probably never actually happen, so I'm punting for now. Nothing should actually break.

The utf8 stuff will be slow, but we only pay for it when we need it.

Test Plan:
Ran unit tests. I changed a few unit tests to use a non-combining character (snowman) for clarity, and some results are different now (since we get combining characters right).

{F44064}

Reviewers: btrahan, Afaque_Hussain

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2379

Differential Revision: https://secure.phabricator.com/D6019
Print --conduit-uri in install-certificate instructions

Test Plan:
  $ arc diff # without certificate
  $ arc --conduit-uri=http://phabricator.local/ diff # without certificate

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D6037