Merge branch 'master' into convlab_exp

convlab/dialog_agent/env.py

convlab/policy/plot_results/README.md

convlab/policy/plot_results/example_map.json

convlab/policy/plot_results/plot.py

convlab/policy/ppo/setsumbt_end_baseline_config.json

convlab/policy/rule/multiwoz/policy_agenda_multiwoz.py

convlab/policy/vector/vector_base.py

data_loaders/utterance_loader.py

requirements.txt