Default pin selection to R3 headers instead of A4/A5
ICSP header for pass-through
Cut-track jumpers to isolate I2C pullups
Use IOREF as VCC for compatibility with both 3.3V and 5V hosts
Relocate Pwr LED so it's not visually associated with VIN / DC IN
Add I2C address table on back of PCB
Reverse order of I2C address pins to match bit positions (A2 A1 A0)
Merge branch 'master' of github.com:freetronics/RelayDriverShield8