* switched zero-page from hardcoded assignments to symbols
* moved most non-hotpath stuff out to .data
* merged ptr and pixel_ptr
Slight slowdown in Atari800MacX from 5m13s to 5m15s
This is a first step toward moving the UI to C and
adding file and network I/O in C. The fractal core
will remain in assembler as well as the multiplier.
