bitforce: Abstract fd access mostly down to BFgets/BFwrite
bitforce: Replace BF{open,close} with more abstract bitforce_vcom_{open,close}
bitforce: Avoid checking fd by adding is_open flag
bitforce: Abstract most of VCOM layer away from driver code
bitforce: Let the lowlevel interface deal only with the actual device cgpu_info
bitforce: Hide vcom interfaces behind new struct bitforce_lowl_interface
bitforce: Support for PCI interface via UIO
util: bfg_slurp_file function to quickly read a file
lowl-pci: New lowlevel driver for raw PCI devices
bitforce: Tie in UIO with lowl-pci