Exception for I2C NACK handling/signalling

[bludin]

Some I2C devices, e.g. the newer Sensirion sensors, use NACK for specific signaling. For instance, upon an I2C write, the CRC byte is NACKed when incorrect. Or an I2C read header is NACKed when no data is available (yet). Therefore, it would be helpful, if a specific exception would be raised that would further indicate the byte of the transmission that got NACKed. Currently, there's a generic OSError No5 that indicates a failure of the I2C transmission.