Build/Tools: Update PHPCS ruleset for WP Core and related Composer setup.

`.gitignore` + `svn:ignore`:
* Add the typical filenames of overloaded PHPCS configs to `.gitignore`.

Composer:
* Use the `develop` (Packagist `dev-master`) version of WPCS as it contains lots of bugfixes.
* Remove the PHPCS dependency. This is a dependency of WPCS, not of WP Core itself. This will also make sure that the PHPCS version used is always one which is supported by WPCS.
* Refreshed the `composer.lock` file.

PHPCS ruleset:
* Removed a reference to a sniff which doesn't exist in WPCS yet.
* Use the PHPCS 3.x `basepath` option to clean up the file paths PHPCS shows in the reports.
* Use the PHPCS 3.x `parallel` option to enable parallel scanning whenever possible to speed up the scans.
* Whitelist the `wp-includes/l10n.php` file from issues being reported by the `WordPress.WP.I18n` sniff.

Fixes #44366.

git-svn-id: https://develop.svn.wordpress.org/trunk@43348 602fd350-edb4-49c9-b593-d223f7449a82

phpcs.xml.dist

@@ -4,10 +4,15 @@
 
 	<rule ref="WordPress-Core"/>
 	<rule ref="WordPress.CodeAnalysis.EmptyStatement"/>
-	<rule ref="WordPress.Commenting.DocblockFormat"/>
 
 	<arg name="extensions" value="php"/>
 
+	<!-- Strip the filepaths down to the relevant bit. -->
+	<arg name="basepath" value="./"/>
+
+	<!-- Check up to 20 files simultanously. -->
+	<arg name="parallel" value="20"/>
+
 	<!-- Show sniff codes in all reports -->
 	<arg value="ps"/>
 
@@ -69,6 +74,12 @@
 		<exclude-pattern>/tests/phpunit/tests/db\.php</exclude-pattern>
 	</rule>
 
+	<!-- Whitelist the I18n functions file from issues identified by the I18n sniff
+		(such as calling the low-level translate() function). -->
+	<rule ref="WordPress.WP.I18n">
+		<exclude-pattern>/src/wp-includes/l10n\.php</exclude-pattern>
+	</rule>
+
 	<rule ref="Generic.Functions.FunctionCallArgumentSpacing">
 		<exclude-pattern>/wp-config\.php</exclude-pattern>
 		<exclude-pattern>/wp-config-sample\.php</exclude-pattern>