GiggleBot MicroPython Firmware v0.2.0

• Add sphinx documentation for readthedocs.org which includes some tutorials and the API description of gigglebot.py/gigglebot_advanced.py/distance_sensor.py modules.
• Add less complex module called the gigglebot.py and rename the old one to gigglebot_advanced.py.
• Optimize gigglebot.py module for the microbit board to use less RAM.
• Fix formatting and semantic issues in the documentation.
• Fix syntax and logic issues in gigglebot_advanced.py module (which is the old module called gigglebot.py).
• Minify python modules before integrating them into the firmware.
• Add usedspace.txt file as build artifact to indicate the size in bytes of the firmware.