PiFace Digital I/O v3.0.0

v3.0.0

• Updated for compatibility with pifacecommon v4.0.0 (which uses the MCP23S17
  class).

• All occurrences of board_num have been replaced with hardware_addr which
  is more appropriate.

• PiFace Digital is initialised when you instantiate the object. You do not
  need to call pifacedigitalio.init() any more unless you're using digital_read
  or digital_write.

• PiFaceDigital inherits registers from MCP23S17 so you can access all the
  registers on the chip. For example GPPUP:

  >>> pfd = PiFaceDigital()
  >>> pfd.gppub.value = 0xff
  >>> pfd.gppub.bits[4].value = 1
  

• InputEventListener now requires that you provide a chip object, not
  a hardware_addr (board_num). This defaults to PiFaceDigital(hardware_addr=0).

• Interrupt events contain a chip object representing the calling chip instead
  of the hardware_addr (board_num). You can still access the
  hardware_addr (board_num) like so:

  >>> def my_callback(event):
  ...     print(event.chip.hardware_addr)
  

• Removed LED, Relay and Switch classes. They added arbitrary restrictions and
  were not very useful. pifacecommon.mcp23s17.MCP23S17RegisterBit is more
  appropriate.

• Updated examples to reflect new changes.

• See the docs (particularly the examples) for more information.