Adds code style checking

.gitignore

@@ -22,3 +22,8 @@
 npm-debug.log
 yarn-error.log
 ###< symfony/webpack-encore-bundle ###
+
+###> friendsofphp/php-cs-fixer ###
+/.php_cs
+/.php_cs.cache
+###< friendsofphp/php-cs-fixer ###

.php_cs.dist

@@ -0,0 +1,42 @@
+<?php
+
+return PhpCsFixer\Config::create()
+    ->setRules([
+        '@Symfony' => true,
+        'method_argument_space' => ['ensure_fully_multiline' => true],
+        'array_syntax' => ['syntax' => 'short'],
+        'list_syntax' => ['syntax' => 'short'],
+        'no_null_property_initialization' => true,
+        'ternary_to_null_coalescing' => true,
+        'no_useless_else' => true,
+        'no_useless_return' => true,
+        // Risky Rules
+        'pow_to_exponentiation' => true,
+        'psr4' => true,
+        'random_api_migration' => true,
+        'self_accessor' => true,
+        'silenced_deprecation_error' => true,
+        'no_homoglyph_names' => true,
+        'no_alias_functions' => true,
+        'modernize_types_casting' => true,
+        'is_null' => true,
+        'dir_constant' => true,
+        'function_to_constant' => true,
+    ])
+    ->setRiskyAllowed(true)
+
+    ->setFinder(
+        PhpCsFixer\Finder::create()
+            ->in([
+                __DIR__.'/config',
+                __DIR__.'/bin',
+                __DIR__.'/src',
+                __DIR__.'/public',
+                __DIR__.'/tests',
+            ])
+            ->append([
+                __FILE__,
+                __DIR__.'/deploy.php',
+            ])
+            ->notPath('config.php')
+    );

composer.json

@@ -6,6 +6,7 @@
         "ext-iconv": "*",
         "ext-json": "*",
         "czproject/git-php": "^3.12",
+        "friendsofphp/php-cs-fixer": "^2.15",
         "php-http/httplug-pack": "^1.1",
         "psr/simple-cache": "^1.0",
         "robinvdvleuten/ulid": "^3.0",
@@ -25,6 +26,7 @@
         "symfony/yaml": "^4.0"
     },
     "require-dev": {
+        "phpro/grumphp": "^0.15.2",
         "symfony/browser-kit": "^4.1",
         "symfony/debug-pack": "^1.0",
         "symfony/phpunit-bridge": "^4.0",