SoundPlayer: Scale y coordinate to prevent drawing outside clip rect

Previously if sample.left amplitude was more than 0.5 we would draw
outside the painters clip rect.

Applications/SoundPlayer/SampleWidget.cpp

@@ -31,7 +31,7 @@ void SampleWidget::paint_event(GPaintEvent& event)
  for (int x = 0; x < samples_to_draw; ++x) {
  // FIXME: This might look nicer if drawn as lines.
  auto& sample = m_buffer->samples()[x];
- Point p = { x, frame_inner_rect().center().y() + (int)(sample.left * frame_inner_rect().height()) };
+ Point p = { x, frame_inner_rect().center().y() + (int)(sample.left * frame_inner_rect().height() / 2) };
  painter.set_pixel(p, Color::Green);
  }
 }