Adafruit-circuitpython-esp32spi

The following changes were made:
* Only allow one TLS connection at a time. Nina FW doesn't work well with multiple.
* Raise OSError(23) when out of socket slots.
* Close a socket when a send doesn't complete.
* Don't raise an exception when close fails.

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-esp32spi`.

Read the [docs](http://circuitpython.readthedocs.io/projects/esp32spi/en/latest/) for info on how to use it.

* Change `recv` to better match CPython sockets. If fewer bytes are available than the requested bufsize, then those bytes will be returned immediately. The old behavior was to wait for a time out and then return the bytes.

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-esp32spi`.

Read the [docs](http://circuitpython.readthedocs.io/projects/esp32spi/en/latest/) for info on how to use it.

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-esp32spi`.

Read the [docs](http://circuitpython.readthedocs.io/projects/esp32spi/en/latest/) for info on how to use it.

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-esp32spi`.

Read the [docs](http://circuitpython.readthedocs.io/projects/esp32spi/en/latest/) for info on how to use it.

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-esp32spi`.

Read the [docs](http://circuitpython.readthedocs.io/projects/esp32spi/en/latest/) for info on how to use it.

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-esp32spi`.

Read the [docs](http://circuitpython.readthedocs.io/projects/esp32spi/en/latest/) for info on how to use it.