* Add system font overflow
1. currently only iOS, Mac and Android platform are supported
add mac label overflow shrink
modify system font overflow test
fix warning and possible memory leaks
add ios system label overflow support
add iOS system font overflow support
fix iOS system font overflow
fix Mac System font overflow
add android system font clamp
add Android system font shrink
cleanup iOS shrink related code
fix Android system font clamp
add core text to project template
fix iOS tests project
fix mac and iOS shrink
improve iOS and Mac clamp feature
fix header file include path
* modify the comments, make it more clearer
子龙山人