Bridge.put() was broken by #2781 because it used transfer() 2-parameters overloaded version, which imply that rxlen == 0.
But the Linux Bridge responded, so the check (i >= rxlen) was true and the function timed out after retrying 50 times.
Every bridge command (python side) has been checked and now SHOULD strictly follow this rule and never ignore silently the received data
Update FileIO::doBuffer() to check for TRANSFER_TIMEOUT and set buffered to 0, and optimize by incrementing readPos instead of moving all of the data one byte to the left in the buffer to skip the error code byte.
