* modify label tool

* fix label tools bug

* add RemoteSensing

* optimize data clip and normalize method for remote sensing

* fix label problem using mobile devices

* add README.md

* polish README.md, optimize main.py and transforms.py, add transforms.md

* add demo dataset

* add create_dataset_list tool, requirements.txt

* add channel-by-channel normalize and clip, remove RemoteSensing import

* update vdl to 2.0

* polish README

* add tool to randomly split dataset and generate file list

* open eval_best_metric while traing, fix typo

* remove python2.7 ci