PHPCS: document run parameters in project ruleset

[jrfnl]

This makes it easier for contributors to run the PHPCS command for the project.

Includes:

• Adding the Tests directory to the run - excluding the test case files in fixtures.
• Cleaning up the result report by using the basepath configuration.
• Making the run faster by using parallel scanning if available,

[sirbrillig]

Nice! I didn't know about those options. Thank you.

[sirbrillig]

Hm... I just got the CI tests to run on contributor PRs and this one fails for php7 with

Script ./vendor/bin/phpcs --standard=./VariableAnalysis handling the lint-self event returned with error code 3

[jrfnl]

Hm... I just got the CI tests to run on contributor PRs and this one fails for php7 with

Hang on, yes, that's my bad, though probably fails on PHP 5 too, but may do so silently.

There are two ways to solve this, but I need some input to know which to use:

1. The lint-self command doesn't use the phpcs.xml.dist file, but points to a standard, so I could add the command line arguments back.
2. I could remove the lint-self command and just add the VariableAnalysis standard to the phpcs.xml.dist file. That way there will be only one PHPCS run which does everything in one go.

@sirbrillig Have you got a preference ? I'd recommend option 2.

[jrfnl]

I've added a second commit implement option 2 for now. Let me know what you think.

[sirbrillig]

Oh, cool. I didn't know you could do that. I like option 2. Thanks!

[jrfnl]

Oh, cool. I didn't know you could do that. I like option 2. Thanks!

Well, as the DealerDirect plugin registers the standard with PHPCS correctly, it's available, so yes, it can be added to the ruleset ;-)