Use a TEST variable

This allow me to generate other test names, just like my other
projects.
Add a single Chisel test

This consists of a pretty simple counter test.  The general idea is to
at least attempt to match libflo to the latest version of Chisel.
Note that this currently runs against a legacy version...
Run libflo against its own output

I figure this is a good policy: libflo should be able to parse
anything it outputs.