function imageformats.png.read_png_header is not accessible

[Jan Jurzitza]

when i try to call read_png_header with a MemStream it says that its not accessible. I can't use any other method because thats the only method accepting a stream and I only have the file in memory and not on disk

[Deleted user]

I added read_png_header_from_mem and a bunch of similar functions, see fe055df.