[3.1.0] Further cleanup, making standalone work again

- Remove includes call in HTMLPurifier.auto.php
- Relax ConfigSchema treatment in generate-includes.php
- Clean up some empty comments (there are probably more)
- De-indent some extends
- class_exists() should now attempt to use autoload
- schema.ser is now a standalone file
- tests/index.php can be run from any directory

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1540 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier.php

@@ -42,7 +42,6 @@
 // constants are slow, but we'll make one exception
 define('HTMLPURIFIER_PREFIX', dirname(__FILE__));
 
-// every class has an undocumented dependency to these, must be included!
 /**
  * Facade that coordinates HTML Purifier's subsystems in order to purify HTML.
  *