Remove pattern_factory::create(void)

It turns out this was no longer being used, so I just went ahead and
got rid of it entirely.  This was originally designed to create random
circuits but I think using the examples is probably better.
Create IN ops with a width

Seeing as how I've forced all input nodes to have a width, I might as
well use that fact to generate proper operations.  This sometimes
helps width inference for operations that otherwise couldn't be
inferred (for example, a RSH test I'm writing).
Fix the Chisel implementation of RSH

This was a brain-o, I emitted "<<" for RSH, which is actually a left
shift.