use attrs for defining things like Episodes and Goals as inheritance works beautifully and classes get a lot of helpful methods for free.

* static PointGoal sensor, Top Down map measure
* top down map measure

* Made simple agents suitable for challenge submissions.

* Update docker

* Addressed the comments, chaned flag names, switched to benchmark

* Removed .swp file, added swp to gitignore.

* Adding arxiv identifier

* commit of image-to-video changes

* black

* added requirement

* fixed docstring spacing

Fix for navigation test that fails occasionally because of the test location is not navigable in some cases.

Benchmark and challenge implementations; PPO agents, Random, ForwardOnly, GoalFollower agents; High resolution top down map and bird-eye visualizations; Collisions measure introduced; SPL success criteria fix; Added deleter that closes subprocesses