Adafruit-circuitpython-circuitplayground

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

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

Put `.frozen` before `lib/` in `sys.path` only if necessary, and only if both are in `sys.path`. This allows testing of non-frozen libraries in `/`, and does not adjust the path if `.frozen` is already before `/lib`.

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

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

Tone sample length is now checked to make sure max DAC sample rate is not exceeded and adjusted as needed.

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

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

Added `deinit()` to `stop_tone` and `play_file` to eliminate issues when using both in the same program.

To use in CircuitPython, simply include `from adafruit_circuitplayground.express import cpx` at the top of your file. The library is built into CircuitPython for Circuit Playground Express.

Read the [docs](https://circuitpython.readthedocs.io/projects/circuitplayground/en/latest/index.html) for info on how to use it.

Library size reduced by about 630 bytes when loaded into memory, about 12% smaller.

No functionality changes except that graceful error checking for CircuitPython versions before 2.2.0 has been removed. These versions will still fail, but less elegantly.

Thanks kattni for testing and review!

Updates to `start_tone` and `play_file` to allow them to work with the changes to `audioio` made for 3.0. Backwards compatibility maintained for 2.x.

To use in CircuitPython, simply include `from adafruit_circuitplayground.express import cpx` at the top of your file. The library is built into CircuitPython for Circuit Playground Express.

Read the [docs](https://circuitpython.readthedocs.io/projects/circuitplayground/en/latest/index.html) for info on how to use it.