support MacOSX build

[sean-e]

• update to C++20 at a minimum (replace use of std::strstream with std::format)
• remove use of MSVC++ language extensions like __super and __interface
• FTDI support problem
  mTroll uses the D2xx FTDI drivers. FTDI does not make 32-bit D2xx drivers for MacOSX.
  Either switch to D3xx API or support 64-bit build.