Rename barcode funcs to same as BARCODE_XXX name
library: barcode funcs array for dispatch, used for ZBarcode_ValidID() also
general: change is_sane() comparison to nonzero from ZINT_ERROR_INVALID_OPTION
MAILMARK: fuller error messages
CODABAR: add option to show check character in HRT
zint.h: use 0xNNNN for OR-able defines
GUI: add guard descent height reset button, add Zint version to window title,
static get_zint_version() method, use QStringLiteral (QSL shorthand),
use SIGNAL(toggled()), add errtxt "popup" and status bar, add icons,
add saveAs shortcut, add main menu, context menus and actions, add help,
reset_view() -> reset_colours(), add copy to clipboard as EMF/GIF/PNG/TIF,
lessen triggering of update_preview(), shorten names of getters/setters,
simplify/shorten some update_preview() logic in switch,
CODEONE disable structapp for Version S
qzint.cpp: add on_errored signal, add missing getters, add test
GRIDMATRIX, MAXICODE, MICROPDF417, PDF417, QRCODE, ULTRA
DOTCODE: use pre-calculated generator poly coeffs in Reed-Solomon for
performance improvement
PDF417/MICROPDF417: use common routine pdf417_initial()
GUI: code lines <= 118, shorthand widget_obj(),
shorten calling upcean_addon_gap(), upcean_guard_descent()
various backend: var name debug -> debug_print
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
Buffered bitmap array should have been type unsigned char not type char
Includes change to manual
In response to (and hopefully fixing) #182 reported by Marcelo Antunes
