New units

[gidesa]

Hello, I send some new units:

• a PCF8574 port expander control class
• a SRF02 ultrasonic ranger control class
• a I2C motor driver circuit (based on Arduino as slave) control class
• the Arduino source for the motor driver
• a direct access by /dev/i2c class, read and write blocks of bytes
  I2C-hardware.zip