Fix colorscopes swapping red and blue on Windows
The colorscopes (waveform, vectorscope, and RGB parade) tried to reinterpret the QImage data as a QRgb, which assumes that the data is AARRGGBB. This is apparently not true on Windows, where the QImage is BGR instead. This caused the colorscopes to have red and blue switched around (reddish images would be plotted as if they were bluish and vice-versa).
The fix is to use QImage::pixel(), which checks QImageData->format and converts to QRgb appropriately.