Refactor into namespaces for PSR-4

tests/data/fenced_code_block.md

@@ -0,0 +1,38 @@
+```
+<?php
+
+$message = 'fenced code block';
+echo $message;
+```
+
+~~~
+tilde
+~~~
+
+```php
+echo 'language identifier';
+```
+
+```c#
+echo 'language identifier with non words';
+```
+
+```html+php
+<?php
+echo "Hello World";
+?>
+<a href="http://auraphp.com" >Aura Project</a>
+```
+
+````
+the following isn't quite enough to close
+```
+still a fenced code block
+````
+
+```
+foo
+
+
+bar
+```