- Cleaned up the initialisation of the script.
- Ensured that the existence of the script is detectable.
- Added tests to ensure plugin loads after position-images (if loaded) and only
  when the document is ready.
- Removed debugging code.
- Removed debug and other obsolete code.
- Tidied up comments.
- Closes #4.
- Removed debugging code.
- Tidied comments.