Adafruit-circuitpython-display-button

* Moved previous `display_button_simpletest.py` to `display_button_customfont.py`
* Made `display_button_simpletest.py` more simple

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle).

To use in CPython, `pip3 install adafruit-circuitpython-display-button`.

Display Button is now a subclass of a Group. **Note:** This _should_ not break any existing code :)

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle).

To use in CPython, `pip3 install adafruit-circuitpython-display-button`.

An issue has been fixed that caused the button to not be drawn if both fill and outline were set to 0 (black). Thanks jpecor.

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle).

To use in CPython, `pip3 install adafruit-circuitpython-display-button`.

SimpleTest example is much easier to use.
* Now showing all buttons
* Fixed the label of one button
* Switched to a much more available font

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle).

To use in CPython, `pip3 install adafruit-circuitpython-display-button`.

Read the [docs](http://circuitpython.readthedocs.io/projects/display-button/en/latest/) for info on how to use it.

* Examples have been updated to work with the latest CircuitPython

* An issue was fixed that resulted in an Out of Range error sometimes

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle).

To use in CPython, `pip3 install adafruit-circuitpython-display-button`.

Read the [docs](http://circuitpython.readthedocs.io/projects/display-button/en/latest/) for info on how to use it.

Allow for changing label of button. Thanks ladyada

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle).

To use in CPython, `pip3 install adafruit-circuitpython-display-button`.

Read the [docs](http://circuitpython.readthedocs.io/projects/display-button/en/latest/) for info on how to use it.