New sniff: change long array syntax to short array syntax

[jrfnl]

Sniff basics	-
Fixable for PHP:	5.4+
Sniff type:	Modernize
Fixer type:	Safe

Short description

PHP 5.4 introduced the short array syntax.

Related PHPCompatibility sniff(s):

• ShortArray

PHP manual references:

• http://php.net/manual/en/language.types.array.php

• Short array syntax has been added, e.g. $a = [1, 2, 3, 4]; or $a = ['one' => 1, 'two' => 2, 'three' => 3, 'four' => 4];.

  http://php.net/manual/en/migration54.new-features.php

Example code:

Detect the following code pattern(s):

$a = array(1, 2, 3, 4);
$a = array('one' => 1, 'two' => 2, 'three' => 3, 'four' => 4);
$a = array(
    'one' => 1,
    'two' => 2,
    'three' => 3,
    'four' => 4
);

And fix these to:

$a = [1, 2, 3, 4];
$a = ['one' => 1, 'two' => 2, 'three' => 3, 'four' => 4];
$a = [
    'one' => 1,
    'two' => 2,
    'three' => 3,
    'four' => 4
];

Notes for implementation of the sniff:

• The PHPCS upstream Generic.Arrays.DisallowLongArraySyntax sniff can be used for this, but should only be invoked when the minimum PHP version for a project is PHP 5.4.