exploration, checkpoints and a new jupyter notebook to aid in experiments

...experiments/pretrained_checkpoints/gc_pgp_checkpoint.ckpt

...riments/pretrained_checkpoints/pdm_offset_checkpoint.ckpt

...iments/pretrained_checkpoints/urbandriver_checkpoint.ckpt

henry_experiments/relavance_construction.ipynb

henry_experiments/run_sim_closed_loop.ipynb

.../planning/simulation/observation/ego_centric_ml_agents.py