External libraries should not be placed in module directory

When using Drush to administer modules and module upgrades, each modules update can break a module. http://drupal.org/node/583706

When drush updates a module is moves the module code to a backup directory and then downloads the module anew.

When the external libraries (tcpdf, wkhtmltopdf, etc...) are in the module directory they need to be manually installed each time.

If the external library were located in a different directory like sites/all/libraries this problem wouldn't occur.

The WYSIWYG module already does this for external libraries.

Also see Libraries API