Fix handling of totals in ProgressReporter

[ryankon]

Here are my changes per pull request #113 and issue #112. Instead of repeatedly setting the total every time a test is run, we can set it once when we start the progress bar, presumably because the number of tests should not be changing during a test run.

[os97673]

perhaps it is better to set total before starting the progress?
Now this order also works but looks unnatural and at some point progress may want to use total in start.
What do you think?

[os97673]

Also do we still have to provide total in progress' constructor if we know that it is always nil there?

[ryankon]

I originally tried to do both those things. I agree that it is a bit unnatural this way, but setting total prior to starting actually breaks the output for the empty test class.

Not setting total to nil in the constructor works too, but it defaults the total to 100, which you see briefly prior to starting, and I preferred the current appearance of briefly seeing the uninitialized progress bar instead.

[os97673]

Thank you for explanation.