Fix PHP version check for function calls with static/variable functions

Summary: D10132 improved this check by eliminating some false postives, but assumes an `n_FUNCTION_CALL` always starts with `n_SYMBOL_NAME`. This is true for `f()`, but not true for `C::m()` or `$v()`.

Test Plan: Added and ran unit tests.

Reviewers: btrahan, joshuaspence

Reviewed By: joshuaspence

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D10467
Fix a typo

Summary: Minor styling fix.

Test Plan: N/A

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10478
Remove a useless function from `ArcanistMergeConflictLinter`

Summary: This function doesn't achieve anything.

Test Plan: N/A

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10477
Fix custom severity rules not being applied

Summary: It seems that `severity.rules` does not override the default linter severities set by the `ArcanistLinter` itself. This seems incorrect and counter-intuitive.

Test Plan: Created a `"severity.rules": { "(.*)": "disabled" }"` configuration and verified that it was being applied.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10475
Add a bunch of additional test cases for `ArcanistTextLinter`

Summary: Self-explanatory, improve test coverage.

Test Plan: Wrote and executed unit tests.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10474
Fix failing unit test

I goofed this up... I think my editor trimmed the trailing whitespace for me.

Auditors: epriestley
Merge branch 'master' of github.com:facebook/arcanist