FM Towns fixes.

I'll be receiving a beta version of the CD-I emulator this weekend (at the earliest). This will speed up development of the CD-I version. I've already paid the registration fee for this excellent piece of software. The CD-I version will be resumed at this point.

Since the CD32 version is going to be delayed, I've decided to fix up some of the problems with the FM Towns version.

I've fixed the speed issues. I turned off the sprite animation system update checks, which was causing all of the sprites to be drawn each frame.

I've also fixed the flashing text and sprites, by adding a changed flag for each double buffered surface.

The play still seems a bit uneven. I need to further optimize some of the routines. I may also convert everything to 8 bit, which will further speed up the updates.