Grove I2C Motor Driver: stepper sample code, version number

Hi,we have no correspoding demo for stepper now,we’ll fine it down later.

The latest version is v1.2.The v1.2 bring a stepper port and switch with it,but the function between them is the same.

Our base shield v1.3 is coming, it brings many I2C ports, UART ports with it,and you can use more devices via Base shield.