Added SUB_EV_SPI_ERR_BUSY event when SPI is busy
Fixed incorrectly using arcBus_stat.events instead of SUB_events
Added abort event to BUS_EV_I2C_MASTER
Fixed check after bus_get_buffer
Add NACK handler and check for NACK during SPI transactions
Check NACK packet length
Send command and error in NACK packet