The patch does not display dots, as they are not that intuitive and users cannot make an estimate of the time left or the position in the training phase. Instead, the regrtest.py, will display the progress as [X/Y], like the default version, but without any warnings, failed tests, skipped tests. Also the start and end report are suppressed.

I don't understand what do you mean by "keyword-only parameter". I added a new flag (-P/--pgo) and propagated it along all the functions that need it. Another approach would have been to use a global variable, lets say "pgo" and use it directly. This is closer to what you had in mind?