- Fixed not working Grayscale visual (was crashing)

- Fixed not working Grayscale visual (was crashing)
- Fixed wrong display of images with alpha in StaticGray and GrayScale visuals
- Hermes lib is used now only to convert if the visual is TrueColor and no
  dithering is necesarry. This is because currently hermeslib doesn't
  support to convert to an indexed destination image (so it can't convert to
  PseudoColor, StaticGray and GreyScale visuals). It can convert to
  StaticColor since this visual uses masks as the TrueColor visual, but
  without dithering. Also hermeslib only supports dithering for just 2
  combinations of source/destination bits/masks, none of which are useful
  for wrlib, so no conversion that needs dithering is currently done
  through hermeslib.