further work on plumbing VIC-II sprite chain
add sprite.vhdl to simulation.
more plumbing work for VIC-II sprites.
plumb more signals in VIC-II sprite chain.
work towards connecting pixel/sprite pixel data chain through
VIC-II sprites.
finish plumbing in VIC-II sprite data chains.
make VIC-II sprites copy data through the chain.
Tell each VIC-II sprite its number.