Improve handling of `--background` with `--base`

Summary:
Currently, we run `runDiffSetupBasics()` //after// splitting off background lint and unit tests. However, this means `--base` and any explicit revision name (like "HEAD^") will not be parsed, so the call to `getRelativeCommit()` in order to generate `arc lint --rev XXX` will fail or not work as expected, because it will ignore any arguments.

Instead, parse `--base`, explicit revisions, and other repository API arguments before doing lint and unit tests.

Test Plan:
  - Set global config for `base` to `arc:amended, git:branch-unique(origin/master)`.
  - Created a commit on master.
  - Ran `arc diff HEAD^`.
    - Before this change, the command fails with "Usage Exception: None of the rules in your 'base' configuration matched a valid commit. Adjust rules or specify which commit you want to use explicitly." when it attempts to run lint, because the `HEAD^` argument is never parsed. After
    - After this change, the command succeeds.

Reviewers: vrana

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D3574
Correctly mark patched text in lint console renderer

Summary:
Before:
`    >>> -      4 `**1**`* Copyright 2011 Facebook, Inc.`

After:
`    >>> -      4  * Copyright 201`**1**` Facebook, Inc.`

Test Plan: Rendered patchable message, multiline patchable message, unpatchable message.

Reviewers: andrewjcg, epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3604
make arc commit work on windows with multiline messages

Summary: cd && cmd won't work so use chdir; -m $multiline_message won't work so use -F $tmp_file

Test Plan: this is actually un-tested at the moment.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T1617

Differential Revision: https://secure.phabricator.com/D3592
Retain newline style when generating diffs

Summary: Builds on D3441, D3440. Instead of exploding on "\r?\n" and then imploding on "\n", retain newline style throughout parsing.

Test Plan:
All unit tests pass (the parser has substantial existing coverage). These new tests pass in the git commit-by-commit test case:

  commit 176a4c2c3fd88b2d598ce41a55d9c3958be9fd2d
  Author: epriestley <git@epriestley.com>
  Date:   Wed Sep 5 14:56:08 2012 -0700

      Convert \r\n newlines to \n newlines.

  commit a73b28e139296d23ade768f2346038318b331f94
  Author: epriestley <git@epriestley.com>
  Date:   Wed Sep 5 14:55:31 2012 -0700

      Add text with \r\n newlines.

  commit 337ccec314075a2bdb4a912ef467d35d04a713e4
  Author: epriestley <git@epriestley.com>
  Date:   Wed Sep 5 14:55:13 2012 -0700

      Convert \n newlines to \r\n newlines.

  commit 6d5e64a4a7a6a036c53b1d087184cb2c70099f2c
  Author: epriestley <git@epriestley.com>
  Date:   Wed Sep 5 14:53:39 2012 -0700

      Remove tabs.

  commit 49395994a1a8a06287e40a3b318be4349e8e0288
  Author: epriestley <git@epriestley.com>
  Date:   Wed Sep 5 14:53:33 2012 -0700

      Add tabs.

  commit a5a53c424f3c2a7e85f6aee35e834c8ec5b3dbe3
  Author: epriestley <git@epriestley.com>
  Date:   Wed Sep 5 14:52:57 2012 -0700

      Add trailing newline.

  commit d53dc614090c6c7d6d023e170877d7f611f18f5a
  Author: epriestley <git@epriestley.com>
  Date:   Wed Sep 5 14:52:41 2012 -0700

      Remove trailing newline.

Previously, the newline-related tests failed.

Reviewers: vrana, btrahan

Reviewed By: vrana

CC: aran

Maniphest Tasks: T866

Differential Revision: https://secure.phabricator.com/D3442
Merge branch 'master' of http://github.com/facebook/arcanist