Reduce duplication of the recursive bisect call
Convert the output and selector to null objects

The scattered `stub` calls without values were annoying and didn't
really say anything for the test.
Move, rename, and test the console output object
Report bisection progress

For long test suites, it's nice to have a bit of a guess as to how far
along the process is. We now output just a smidge of information to
let the user know what's going on.

Closes #10
Merge pull request #29 from shepmaster/report-progress

Report progress