to get working using nmake "makefile.vcwin32", added to fork at
https://github.com/gitlost/gs1-syntax-engine;
small updates to Linux, macOS READMEs
GUI: change "chkGS1Strict" to be hidden instead of manually adding
pandoc: latest version
and `out_colour_get_cmyk()`, to lessen chances of rounding
errors (in particular for VC6)
test_large: fix regression in change to test for formatting
`uint64_t` for `printf()`
win32/README: update MinGW/MSYS Qt version