Problem with rendering of GUI

[rdebath]

The most recent version of Classicube seem to be showing a gui.png file incorrectly.

The terrain file is http://51.195.219.231:8000/ocdpack.zip

Problem starts with commit c26944576 Optimise PNG decoding to decode image using the destination image buffer

[UnknownShadow200]

With these macros in Bitmap.c:

#define PNG_Do_Grayscale_8()      rgb = src[0]; Bitmap_Set(*dst, rgb, rgb, rgb,    255); dst--; src -= 2;
#define PNG_Do_Grayscale_A__8()   rgb = src[0]; Bitmap_Set(*dst, rgb, rgb, rgb, src[1]); dst--; src -= 1;

I accidentally swapped src -= 1; and src -= 2; around there (GrayScale_A should be the one consuming 2 bytes per pixel)