Adam7 fails for paletted images

[ThomasHoevel]

logo.zip

When opening the attached image after applying the patch from issue #13 (#13 (comment)), the library fails while reading the image.
The image is interlaced using Adam7.

[ThomasHoevel]

Update: The image dimensions are 360x180.
Decoder allocates 360x180 bytes for the image.
RawPngData calculates with 361 bytes per row and hits an Index out of range exception.

[ThomasHoevel]

I updated the code to make it work by conditionally adding "1" add two places for the image with color palette. Our interleaved true-color test image only works without adding 1.
I don't know if this works for all images.
See PR #17.