1.2.1

EasyAR 1.2.1 includes a fix for EasyAR 1.2.0 when input size is not correct, and also a few optimizations of tracking. The fixed issue will only happen when the target size is not correctly set, and this new version will handle the incorrect input smoothly.

Detailed changes made since EasyAR 1.2.0 include the following.

* fixed flicker and detection issue if the input size ratio is incorrect

* optimized tracking