Cleaning up the display

Very quick update tonight.

Cleaned up the Eye Catcher screen (with my custom hack from earlier projects) and added masking sprites to the Xevious display. The screen width still isn't right... there's some behaviour I haven't quite understood with the Neo Geo sprites but hopefully I'll get that sorted soon.

As you can see, the scrolling looks a lot better without the jumping edges top and bottom. Any jerking you may see is an artifact of the MAME video recorder and/or Google playback. It's silky smooth on the emulator.

I also had a look at the VASM assembler which seems to be popular with some Neo Geo and Amiga developers. It all makes sense but none of the sample projects are set up to use a linker with multiple object files, and right now I don't want to look further into it, so it's gnu AS for now...