Tuple for touch

[caternuson]

Consider having a function that returns a tuple of touched pads. Allows for iterating over all touched pads:

for pad in cpx.touched:
    print("pad {0} touched!".format(pad))

Also allows using the in syntax to check if a pad is touched. Can return ints:

if 1 in cpx.touched:
    print("pad 1 touched!")

or maybe strings:

if 'A1' in cpx.touched:
    print("pad A1 touched!")

or something else?

[kattni]

We had talked about this previously as well. The last example seems to be the most readable. This can definitely be included. Added to list.

[kattni]

The functions were designed but it was determined that they aren't a good fit for this library.

The function code and examples have been posted to the adafruit/circuitpython repo here adafruit/circuitpython#367 for future use. Discussed suggestions for future use are outlined in the issue.