Created by: shippingwang

This PR

• add print interval, one can set it by indicating --print_interval=10
• refine override function, for now, fields have to totally match YAML content
  • can add a new single field, like --use_ppp=1
  • can delete the existing field, It will help developers adjust hyperparameters by modifying run.sh instead of changing YAML
  • can add a new Dict field, like --use_ppp.use_qqq=1