Simple compare implementation
replaced chain mode with long mode for move
Implemented the basic move operation

I also streamlined the different move modes. I eliminated the register to
immediate move because it doesn't actually make any since with a 16 bit memory
space.
Eliminated the upper "store" registers

These overlays no longer make sense with a 16-bit program space. So I doubled
the register count to 8 instead.
Implemented basic arithmetic operations
Fixed up instruction alignment and sizes
Got a basic working version of iris