remove adafruit_itertools layer from import

[FoamyGuy]

resolves #15

Before change import syntax is like this:

from adafruit_itertools.adafruit_itertools import count 

with this change this is the import:

from adafruit_itertools import count 

We may want to consider renaming adafruit_itertools_extras to just extras.py? That way it's import would end up like this:

from adafruit_itertools.extras import repeatfunc 

This one is a bit outside the scope of matching CPython if I understand correctly. I haven't made that change, but can if we want it that way.

This PR is a breaking change if merged so it would need a major version bump and find/update usages in learn guide ode and anywhere else it's used.

[FoamyGuy]

Latest commit resolves an issue with the extras module not importing the main module utilities successfully after the change.

I tested the version from latest commits successfully with a Feather ESP32-S2 TFT and the simpletest script from this repo.

[tekktrik]

Ooo looks fun! I can take a look at this.

[tekktrik]

Good idea removing that layer and moving it into __init__.py! Didn't test but looks good to me!