progress: force a repaint of a printed progress bar after a clear() This avoids some visual flickering of the progress bar in convert and probably some other operations. Previously, a line of output would erase the progress bar, and then it would wait `progress.refresh` seconds (default of 0.1) before redrawing the progress bar. Now if we've ever painted a progress bar, we schedule the progress bar for immediate repainting on the next progress call, which helps lend the illusion that the progress bar is "always" there. In practice, it's merely there more of the time, but it ends up being a lot easier to read during convert.