FTDI USB driver with bitbang mode

libFTDI is an open source library to talk to FTDI chips,
including the popular bitbang mode. The library is linked
with your program in userspace, no kernel driver required.
Supported chips are:

 * FT232BM,
 * FT245BM,
 * FT2232C,
 * FT2232D,
 * FT245R,
 * FT232H,
 * FT230X.