Adding device driver for PCF8574 I2C I/O expander port.
Adding support for LCD (20x4, 16x2) with TWI expander.

1. Abstracting communication with HD44780 LCD to IO device.
2. Add support for Port and MJKDZ (PCF8574 based) I2C LCD communication.
3. Adjusting example sketches.
Adding some news.