Remove old test ./go scripts

Before I started writing proper Bats tests, I used this script and its
command scripts to play around with my ideas. I thought it might serve
as a test driver, or a demo, but eventually I created Bats helpers to
generate isolated test scripts on the fly, and the top-level `./go`
script began to serve as its own extensive demo.

Hence, it's time to say goodbye to these old chestnuts.

Author: mbland