enable warm starting adversarial algorithms w/ behavior cloning

[samuelarnesen]

Description

Addresses issue #587

Enables out-of-the-box warm starting of a GAIL/AIRL training run w/ behavior cloning

Testing

New unit test

[codecov]

Codecov Report

Merging #602 (5d3b8bb) into master (622092c) will increase coverage by 1.21%.
The diff coverage is 100.00%.

❗ Current head 5d3b8bb differs from pull request most recent head 24a88b8. Consider uploading reports for the commit 24a88b8 to get more accurate results

@@            Coverage Diff             @@
##           master     #602      +/-   ##
==========================================
+ Coverage   96.31%   97.52%   +1.21%     
==========================================
  Files          89       85       -4     
  Lines        8618     8130     -488     
==========================================
- Hits         8300     7929     -371     
+ Misses        318      201     -117     

Impacted Files	Coverage Δ
src/imitation/scripts/config/train_adversarial.py	71.95% <100.00%> (+12.69%)	⬆️
src/imitation/scripts/train_adversarial.py	95.18% <100.00%> (+1.59%)	⬆️
src/imitation/scripts/train_imitation.py	96.20% <100.00%> (+3.55%)	⬆️
tests/scripts/test_scripts.py	100.00% <100.00%> (ø)
src/imitation/scripts/parallel.py	64.81% <0.00%> (-1.23%)	⬇️
.../imitation/scripts/train_preference_comparisons.py	96.87% <0.00%> (-0.35%)	⬇️
src/imitation/algorithms/mce_irl.py	95.95% <0.00%> (-0.22%)	⬇️
src/imitation/data/types.py	98.19% <0.00%> (-0.02%)	⬇️
tests/test_experiments.py	100.00% <0.00%> (ø)
tests/data/test_rollout.py	100.00% <0.00%> (ø)
... and 49 more

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[ernestum]

@samuelarnesen @AdamGleave are we still interested in merging this PR? If so I would review it and resolve the conflicts.

[AdamGleave]

It's a feature I'd like to have. But the solution ended up quite messy, I think we might need a more significant refactor of our scripts to accommodate it cleanly, so I'm inclined to icebox it.

FYI samuelarnesen worked on this during his work trial which is now over, so out of respect for his time let's try and resolve this without his involvement.

[ernestum]

I rebased/squashed this onto the current master. Before properly cleaning up I would like to decide if we keep sacred or not in #79