Have test output be more verbose

This actually shows what's run and output from the tests, to aid
debugging.
fprintf to stderr before all abort() calls

This makes tracking them down a bit easier when I don't have a
debugger.
Fix a width inference bug

This one was actually pretty straight-forward: I'd accidentally
infered the wrong width when attempting to cross-coorelate operands.
The fix was to just use the correct width (which I'd already looked up
but for some reason wasn't using).