File updates

I've made some minor improvements to the files, including:

• Updated sausage scoring for solo play. Now, you must have four visible sausages to score a point instead of joining them up. 
• Lighter card backgrounds for improved porky produce visibility.
• Aesthetic tweaks to the card backs.
• The rules were reordered with some minor corrections.
• Improved score sheet layout.

Thanks!
Kev