More Berzerk

After a bit more work on Berzerk I've now got the top/bottom walls drawing properly and fixed (or at least I thought I had) the rest of the wall drawing which was a byte or so off. It's still not right though as I found out on one particular screen!! :(

Preliminary enemy bullets are in (coarse movement atm) with collision detection working for bullets against walls (nice and easy to tell the pseudo 2600 hardware about this one). The same code can be used for your guys bullets. Put in the sprite frames for your guy. Score/lives/bonus is printed now (that's been in for a while).

Nearly done. Finding the best way to tell the 2600 code about C64 collisions is the main thing to do. I know how to fool it into thinking things have happened but I think I need to actual convince the pseudo hardware that it has rather than forcing the result of some variables to be what they would be on the 2600.