To build

  cp src/gcconfig.pri.in src/gcconfig.pri
  cp qwt/qwtconfig.pri.in qwt/qwtconfig.pri

Edit both src/gcconfig.pri and qwt/qwtconfig.pri as necessary, then

  qmake
  make

To uninstall the older FTDI VCP drivers on Mac OS X, open a Terminal and type:

  sudo mv /System/Library/Extensions/FTDIUSBSerialDriver.kext /tmp

Type your password when prompted, then restart your computer.
