Palette bit depth & transparency mask changes
Detail:
- Honours the bit depth of the source image rather than setting 8bpp flat. This is based on the palette size and is now restricted to 2, 4, 16 or 256 colours. Non-paletted images are 24 bit colour.
- Add option to add tRNS chunk for paletted images to have a mask set by substituting one of the paletted entries for a transparency.
- Change palette docs in CompressPNG - 0x00BBGGRR not just a 3 byte entity.
- Refuse to start a compression run if ZLib module is missing. Admin: Submission for PNG bounty.