message: fixed alpha channel loading with ImageMagick
  Conflicts:
  apps/common/miniSG/miniSG.cpp
diff: @@ -91,14 +91,14 @@ namespace ospray {
  *dst++ = pixel.green * rcpMaxRGB;
  *dst++ = pixel.blue * rcpMaxRGB;
  if (tex->channels == 4)
  - *dst++ = pixel.opacity * rcpMaxRGB;
  + *dst++ = (MaxRGB - pixel.opacity) * rcpMaxRGB;
  } else {
  unsigned char *dst = &((unsigned char*)tex->data)[(x+(tex->size.y-1-y)*tex->size.x)*tex->channels];
  *dst++ = pixel.red;
  *dst++ = pixel.green;
  *dst++ = pixel.blue;
  if (tex->channels == 4)
  - *dst++ = pixel.opacity;
  + *dst++ = 255 - (unsigned char)pixel.opacity;
  }
  }
  }
  @@ -282,14 +282,14 @@ namespace ospray {
  *dst++ = pixel.green * rcpMaxRGB;
  *dst++ = pixel.blue * rcpMaxRGB;
  if (tex->channels == 4)
  - *dst++ = pixel.opacity * rcpMaxRGB;
  + *dst++ = (MaxRGB - pixel.opacity) * rcpMaxRGB;
  } else {
  unsigned char *dst = &((unsigned char*)tex->data)[(x+(tex->size.y-1-y)*tex->size.x)*tex->channels];
  *dst++ = pixel.red;
  *dst++ = pixel.green;
  *dst++ = pixel.blue;
  if (tex->channels == 4)
  - *dst++ = pixel.opacity;
  + *dst++ = 255 - (unsigned char)pixel.opacity;
  }
  }
  }
  