GSoC status report - Week 9

[Paris Oplopoios]

Add 32bpp export support in PngImageWriter (patch
<https://www.blogger.com/blog/post/edit/4095507683943629087/7931884723456155530#>
)
Use bitmap width instead of scanline size in combineScanlineChannels (patch
<https://gerrit.libreoffice.org/c/core/+/137278>)

PngImageWriter should be finished at this point

Next:
Combine GraphicDescriptor and GraphicFormatDetector