* add IMPALA algorithm and some common utils

* update README.md

* refactor files structure of impala algorithm; seperate numpy utils from utils

* add hyper parameter scheduler module; add entropy and lr scheduler in impala

* clip reward in atari wrapper instead of learner side; fix codestyle

* add benchmark result of impala; refine code of impala example; add obs_format in atari_wrappers

* Update README.md

* add a3c algorithm, A2C example and rl_utils

* require training in single gpu/cpu

* only check cpu/gpu num in learner

* refine Readme

* update impala benchmark picture; update Readme

* add benchmark result of A2C

* move get_params/set_params in agent_base

* fix shell script cannot run in ubuntu

* refine comment and document

* Update README.md

* Update README.md

* fix PPO bug; add more benchmark result

* refine code

* update benchmark of PPO, after fix bug

* refine code

* add more dqn benchmark result; unify train scripts

* resize benchmark picture

* resize benchmark picture, refine comments of args

* change dependence, mujoco only support python3 now

* remove not used files, add benchmark for DQN and DDPG, add Parameters management Readme

* Update README.md

* Update README.md

* add parl dependence in examples, use np shuffle instead of sklean

* fix codestyle

* refine readme of nips example

* fix bug

* fix code style

* Update README.md

* Update README.md

* Update README.md

* refine document and remove outdated design doc

* Update README.md

* Update README.md

* refine comment

* release version 1.0

* gif of examples

* Update README.md

* update Readme

* add PPO example

* Update Readme

* Update Readme

* fix codestyle

* Update Readme

* refine action mapping

* add more unitest case

* remove unnecessary params initialize, add more comments, add benchmark result

* rename

* remove PARL dependence in readme of examples

* add DDPG example, fix some tiny bug

* add license

* unify code structure

* unify code structure

* refine gputils, fix seed in QuickStart

* use white noise in DDPG

* fix codestyle