Need DRUPAL_ROOT in various places

I have an external PHP script that bootstraps Drupal, and that lives in a subfolder of my Drupal install dir.

After bootstrapping, this script calls some functionality from the Wysiwyg module. I discovered that the functionality doesn't currently work if called from a script that lives outside of the Drupal root, as there are several places where it should be (but is not) prepending DRUPAL_ROOT to the file path.

Attached patch fixes this, by appending DRUPAL_ROOT where necessary.

This also depends on: #1924212: Need DRUPAL_ROOT in file_scan_directory →