CD32 finished, needs testing. FM Towns progress.

I added the last of the functionality to the CD32 version of Frog Feast. The sky changes color over time, and it should display correctly on a PAL display. The PAL change involved changes to more code than I expected. The allocated display memory is now 256 pixels high, instead of the 224 it was before. I will be testing on a real CD32 player over the next week.

I started implementing the sprite functionality into the FM Towns version. Understanding the functionality of the sprite system will take some investigating.