nxt-python 3.0.0a3

Maximilian von Unwerth (1):
      Changed rtype in docstring of find_brick for autocompletion

Nicolas Schodet (5):
      Make Bluetooth dependencies optional
      Explicitly import nxt.sensor sub-modules in tests
      Do no use bytes.hex parameter, get back Python 3.7 support
      Do not use argparse.BooleanOptionalAction for Python 3.7 support
      Improve and document get_sensor