Move `ArcanistSpellingDefaultData` into a configurable JSON file

Summary: Currently, the `ArcanistSpellingLinter` loads data from `ArcanistSpellingDefaultData`, with no way to configure the linter from an `.arclint` file. Instead we should define a format for a "dictionary" file, of which the `ArvcanistSpellingLinter` can load and of which the paths are easily configured through `.arclint`.

Test Plan:
Updated the test case and ran `arc unit`.

NOTE: I have removed the `LINT_SPELLING_PICKY` and `LINT_SPELLING_IMPORTANT` constants and replaced them with `LINT_SPELLING_FULL` and `LINT_SPELLING_PARTIAL`. This was done because it simplifies the implementation considerably and makes customization of the `ArcanistSpellingLinter` simpler, but also because these constants were not widely used in the existing implementation.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9805
Move `PhutilLibraryMapBuilder` to `libphutil`

Summary: See D9813 for a detailed explanation.

Test Plan:
```
> ./bin/arc liberate
Finding source files...
Found 194 files.
Loading symbol cache...
Found 194 files in cache.
Building library map...
Writing map...
Done.
```

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9815
Regenerate library map

Summary: Ran `arc liberate` after D9805.

Test Plan: `arc liberate`

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9825
Improve the `ArcanistInfrastructureTestCase` unit tests

Summary:
Improve the `ArcanistInfrastructureTestCase` 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: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9826
In Arcanist, ignore extensions when unit testing the library map

Summary: See D9834. Arcanist version.

Test Plan: See D9834.

Reviewers: joshuaspence

Reviewed By: joshuaspence

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D9835
Minor change to `ArcanistInfrastructureTestCase::testLibraryMap`

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

Test Plan: See D9844.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9846
Remove deprecated lints from `ArcanistXHPASTLinter`

Summary: After D9576, `LINT_PHP_53_FEATURES` and `LINT_PHP_54_FEATURES` are deprecated. They have been replaced by `LINT_PHP_COMPATIBILITY`.

Test Plan: `arc unit`

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9657
Merge branch 'master' of github.com:facebook/arcanist