TODO

    Test use_ok() with imports better.

    Add BAIL_OUT() (little known Test::Harness feature that basically
    declares that the universe has turned out all wrong and the test
    will now stop what it's doing and just go back to bed.)

    Add a way to ask "Are we passing so far?".  Probably a
    Test::Builder method.

    Finish (start?) Test::FAQ

    Expand the Test::Tutorial

    Restructure the Test::More synopsis.

    Decide if the exit code behavior on failure is a useful default
    case.

    $^C exception control?

    Document that everything goes through Test::Builder->ok()

    Add test name to diagnostic output

    Put a newline before the first diagnostic failure when in Test::Harness

    Trap bare exit() calls.

    Add diag() to details().

    Add is_passing() method to check if we're passing?

    Add at_end() callback?

    Combine all *output methods into outputs().

    Change *output* to return the old FH, not the new one when setting.