LICENSE:BSD-3
based on https://github.com/levinunnink/Smooth-Line-View
I add new function: 1. undo 2. redo 3. clear 4. eraser 5. change color 6. save image to file 7. save image to album 8. load image from album
//Smooth Line View-Prefix.pch
//switch UIBezierPath / CGContext
#define USEUIBezierPath 0
//switch Image push to memory or files
#define PUSHTOFILE 1
