Timer class fixes and MicroPython v1.6
py core:
- Updated to relase v1.6
wipy:
- Improve robustness of WLAN during sleep modes.
- Fix and simplify the Timer API.
- Improve robustness of the I2C driver.
- Rename 'server' class to 'Server' for consistency.
docs:
- Update Timer class documentation.
- Update Server class documentation.