- $_SERVER['DOCUMENT_ROOT'] replaced by DRUPAL_ROOT
- substr replaced by drupal_substr()
- URL validation in backlinkseller_settings_form_validate() replaced with valid_url()

- Removed check_plain() in query for url()
- Delete whitespaces

- Remove unused method

- Added a warning in README

- Moved the example into a replacement.
- Reformat data on output.
- Used theme_image() in settings form.
- Replaced $_SERVER['DOCUMENT_ROOT'] with DRUPAL_ROOT.
- Used url() to build an URL.
- Removed whitespaces.
- Used drupal_html_id().

- Removed not necessary menu type
- Rename $block_name into $delta
- Reformated all arrays
- Check $backlinks for XSS
- Replaced "/" with $base_path
- Use system_settings_form