Software I2C / TWI library for Arduino allows any two pins to be SDA & SCL
C++
Latest commit f1374d8 Jan 26, 2017 @todbot committed on GitHub updated license, per issue #14

README.TXT

SoftI2CMaster

2010-2012, Tod E. Kurt, http://todbot.com/blog/
2014, by Testato: update library and examples for follow Wire’s API of Arduino IDE 1.x


SoftI2CMaster is an Arduino library that implements
a simple "bit-bang" software-only I2C (aka "TWI") Master.

This lets you use any two Arduino pins to be the SDA & SCL 
pins needed to communicate with I2C devices like BlinkMs.

SoftI2CMaster was originally in the BlinkMSoftI2CDemo example
in http://code.google.com/p/blinkm-projects/