Add PHP CS Fixer tool

- Add executable in `util`
- Add config file for a project-wide run of the fixer

.php_cs

@@ -0,0 +1,16 @@
+<?php
+
+$finder = Symfony\CS\Finder\DefaultFinder::create()
+    ->exclude('doc')
+    ->exclude('images')
+    ->exclude('js')
+    ->exclude('library')
+    ->exclude('mods')
+    ->exclude('spec')
+    ->in(__DIR__)
+;
+
+return Symfony\CS\Config\Config::create()
+    ->level(Symfony\CS\FixerInterface::PSR2_LEVEL)
+    ->finder($finder)
+;