Add PHP-CS-Fixer config

.gitignore

@@ -1,3 +1,15 @@
-/composer.lock
-vendor
+# PhpStorm / IDEA
 .idea
+
+# temp files
+.DS_Store
+Thumbs.db
+
+# composer
+composer.lock
+/vendor
+
+# code style fixer
+.php_cs
+.php_cs.cache
+

.php_cs.dist

@@ -0,0 +1,54 @@
+<?php
+
+$finder = PhpCsFixer\Finder::create()
+    ->in([__DIR__ . '/src']);
+
+return PhpCsFixer\Config::create()
+    ->setRules([
+        '@PSR1'                               => true,
+        '@PSR2'                               => true,
+        'array_syntax'                        => ['syntax' => 'short'],
+
+        // keep aligned = and => operators as they are: do not force aligning, but do not remove it
+        'binary_operator_spaces'              => ['align_double_arrow' => null, 'align_equals' => null],
+
+        'blank_line_before_return'            => true,
+        'encoding'                            => true,
+        'function_typehint_space'             => true,
+        'hash_to_slash_comment'               => true,
+        'lowercase_cast'                      => true,
+        'magic_constant_casing'               => true,
+        'method_separation'                   => true,
+        'native_function_casing'              => true,
+        'no_blank_lines_after_class_opening'  => true,
+        'no_blank_lines_after_phpdoc'         => true,
+        'no_empty_comment'                    => true,
+        'no_empty_phpdoc'                     => true,
+        'no_empty_statement'                  => true,
+        'no_extra_consecutive_blank_lines'    => true,
+        'no_leading_import_slash'             => true,
+        'no_leading_namespace_whitespace'     => true,
+        'no_short_bool_cast'                  => true,
+        'no_spaces_around_offset'             => true,
+        'no_unneeded_control_parentheses'     => true,
+        'no_unused_imports'                   => true,
+        'no_whitespace_before_comma_in_array' => true,
+        'no_whitespace_in_blank_line'         => true,
+        'object_operator_without_whitespace'  => true,
+        'ordered_imports'                     => true,
+        'phpdoc_indent'                       => true,
+        'phpdoc_no_useless_inheritdoc'        => true,
+        'phpdoc_scalar'                       => true,
+        'phpdoc_separation'                   => true,
+        'phpdoc_single_line_var_spacing'      => true,
+        'return_type_declaration'             => true,
+        'self_accessor'                       => true,
+        'short_scalar_cast'                   => true,
+        'single_blank_line_before_namespace'  => true,
+        'single_quote'                        => true,
+        'space_after_semicolon'               => true,
+        'standardize_not_equals'              => true,
+        'ternary_operator_spaces'             => true,
+        'whitespace_after_comma_in_array'     => true,
+    ])
+    ->setFinder($finder);