DMATAMATRIX: fix look ahead BASE256 use of dm_text_sp_cnt() on switching;
simplify dm_add_tail()
GUI: check suffixes on save so don't go into error state;
use native path for Save As clipboard message
CODE128: use gs1_check_digit() for NVE18 and EAN14
RMQR: update to new draft ISO/IEC JTC1/SC31N000 (Draft 2019-6-24);
allow for righthand vertical timing pattern in populate_grid()
ULTRA: update max size and min cols based on BWIPP 2021-07-14 update
backend_tcl/zint_tcl.dsp: use /MD instead of /MT for tcl lib compat;
change include/lib path to more standard one
manual.txt: highlight that rMQR is still in development
GUI: use cross-platform smaller font func instead of explicit values for notes
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
