AMPS Todo

- FEATURE [DONE]: Change image output to PNG or add an option to select type
  (version 0.6)
- FIXME [DONE]: Fix the incorrect display of special characters in the signature
  image. (version 0.4)
- FEATURE/FIXME: Improve multilingual support by allowing formatable strings
  via printf()
- FEATURE: Improve 'theme' support beyond the simple CSS file.
- FIXME [DONE]: Change passing of sig_image variable so using register_globals
  is not necessary. (version 0.7)
