`iso3166list` linter and adjusting all others to allow for
multiple optional linters (by checking `data_len` vs `offset`)
library: change invalid `input_mode` reset to return warning;
split func table into 2 - func declarations without prototype
will be error in C23;
make invalid symbology check a separate function using a table
and call near beginning of `ZBarcode_Encode_Segs()`;
in `ZBarcode_BarcodeName()` save some bytes by simplifying
name table and removing "BARCODE_" prefix from entries
output: fix pack logic to use pragma by default (actually more
portable than `__attribute__`)
common.h: remove C99 detection which was artifice of specifying
"-std=", and rejig layout to be more logical
BWIPP: update to latest version
general: change `ZINT_VERSION_BUILD` tests to `#if`s
general: further fiddling with some tables to save a few bytes
CLI: change function arg `optarg` -> `arg` so doesn't shadow
global
general: library now compilable with Comp Cert C (though as it
doesn't support `alloca()` will have multiple memory leaks)
replace double-slash comments with old-skool slash asterisk ones;
define uint16_t etc for Windows ourselves and remove ms_stdint.h &
stdint_msvc.h as no longer used;
(backend (excepting test suite) now C89 compatible)
LICENSE: move from backend to root and move COPYING to frontend, with
copies in frontend_qt & backend_qt, so in where it applies;
add LICENSE section from manual to root README
