* sync 1.6

* sync 1.6

* update readme

* Revert "change PyReader to from_generator (#3490)"

This reverts commit d331b799.

* Update data_reader.py

* Update data_reader.py

* Update utility.py

* change PyReader to from_generator

* fluid.layers.data->fluid.data

* fix_bug

* fix used

* update gan0727

* update gan model

* update gan model time display

* update gan script

* update gan script

* fix py3

* fix bug in cycle and pix

fix bug of gan in python3

GAN model