Update to the demo

Work on the full version of "Tristam Island", which comes out on November 20th, is well underway, and even though there is lots left to do, I won't have problems finishing it on time!

As I go through the code, I sometimes find shortcuts or efficiencies I hadn't thought of before. Today I backported some of these to the demo and updated the demo files across the board. The demo has now slightly (up to 10%) faster parsing, which might be noticeable on the older machines. Enjoy!