Update Adafruit_MCP230xx/Adafruit_MCP230xx.py

direction is supposed to reflect the Input/Output status of the 8 or 16 pins.
In the 16 pin case, config produced 8 bits and lost information (even though
the register in the chip were set correctly). I have proposed code to fix this. 

input returned True or False correctly, but I change the code to return 1 or 0 (as opposed to non-zero or 0)

I also added a optional parameter to input to allow the assertion to be skipped, as I want to experiment with input from any pin 

Also there are many functions only within the scope of input that are not used. Are they needed as part of the class? Should they be removed?