potential fix for intermittent "monome i2c" devices
potential fix for intermittent "monome i2c" devices

previously, we would fire off all the handshake messages for mext
devices at the same time, then wait for the responses. this patch
instead makes the handshake code wait for each message to return
before sending the next.

monome/libmonome,monome/libmonome,monome/libmonome