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
also avoid distributive multiplication with floats to lessen chances of
platform variation (#204 ARM-Cortex crash)
- raster.c: Don't allow for text if scale < 1.0
- raster.c: Cast some indexes to (size_t) to allow for large scale
- vector.c: Check malloc()s and return ZINT_ERROR_MEMORY on fail
- raster/vector.c: various var name changes & other code fiddling
- library.c: Check that scale/height/whitespace/border are reasonable values:
scale (0.01-100), height (0-500), whitespace_width/height (0-100),
border_width (0-100)
- CLI: allow both e.g. '-height' and '--height' (getopt_long_only())
- gif.c: fix GIF_ZLW_PAGE_SIZE -> GIF_LZW_PAGE_SIZE
- GUI: allow whitespace/scale to 100
bmp/emf/ps.c: allow for foreground colour in ULTRA
bmp/gif/pcx.c: allow for BARCODE_STDOUT (fflush/fclose)
emf.c: hexagon rotation field not used; dont't use float index in font loop; Windows stdout binary mode
png.c: remove unused 8-bit; simplify libpng error handling and fclose outfile on error
ps.c: fix buffer overflow on colour_to_pscolor() CMYK
tif.c: fix BLACKISZERO indexes
CODE39: simplify check digit setting
reedsol.c: rs_uint_init_gf() log/alog tables must be zeroed
ZBarcode_Encode: debug: fix access out-of-bounds on non-NUL-terminated source if length < 10
manual.txt/zint.h: document NUL-terminated strings
tests: cover further cases for output (bmp/emf/etc), eci/gb18030/gb2312/sjis, reedsol, AZTEC, CODE39
PLESSEY: add options NCR weighted mod-10, hide check digit(s) in HRT
test suite: now runnable under MSVC 2019, 2017, 2015, MinGW/MSYS
win32/README: update with MSVC 2019 and CMake instructions
