The ```configuration``` is required by the visual studio generator to determine
whether to use a Debug or a Release setup (or a user customized one). It's
required by whatever uses that generator rather then just the GUI code.
Add instructions for the Visual Studio Project File generator to the README
and enable the test on Windows.
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
