There were many run-time warnings in YACReaderLibrary built in Debug
mode with hardware acceleration disabled and with ClassicComicsView
as the active comics view:
QWidget::paintEngine: Should no longer be called
QPainter::begin: Paint device returned engine == 0, type: 1
The ComicFlowWidgetSW::paintEvent() implementation now corresponds to
ComicFlowWidgetGL::paintEvent(), which has been fixed earlier.
QWidget::repaint() calls paintEvent() immediately.
PictureFlow::paintEvent() calls d->renderer->paint(). So the
d->renderer->paint() call in PictureFlow::updateMarks() was redundant.
