Updates for new MCP230xx

[caternuson]

This updates the library to use the new MCP230xx refactor.
adafruit/Adafruit_CircuitPython_MCP230xx#11

[caternuson]

I was able to test with a PID 292, but don't have one of the shield or hats with buttons.

[ecspresso]

@caternuson If you tell me what to do, I could test this with a hat (if needed).

[caternuson]

HAT = Pi. Easiest way is to use git and grab the PR version of the code with this process:
https://help.github.com/en/articles/checking-out-pull-requests-locally
and then set your PYTHONPATH to point to that local directory.

[ladyada]

@brentru will be testing!

[brentru]

@caternuson Did you update an example?

on this branch, I'm hitting against the No Module named error:

Traceback (most recent call last):
  File "code.py", line 15, in <module>
  File "/lib/adafruit_character_lcd/character_lcd_i2c.py", line 74, in __init__
ImportError: no module named 'adafruit_mcp230xx'

Example: https://github.com/adafruit/Adafruit_CircuitPython_CharLCD/blob/master/examples/charlcd_i2c_mono_simpletest.py

Board: Metro M4

[caternuson]

The examples shouldn't need updating. Hopefully. The change is essentially just a tweak to the import syntax for the MCP230xx library which is done in the __init__ of the various classes.

Are you testing the PR version? That looks like the error you'd get if still using the current library.

[brentru]

@caternuson Yup, I'm testing the PR'd version.

[brentru]

@caternuson Works with a shield kit. You may want to add the MCP230xx library to the README's dependency list: https://github.com/adafruit/Adafruit_CircuitPython_CharLCD#dependencies