Add calc_laterality and fix plotting error

[codecov-io]

Codecov Report

Merging #54 (494b39d) into master (5046b4c) will decrease coverage by 9.42%. The diff coverage is 61.50%.

@@            Coverage Diff             @@
##           master      #54      +/-   ##
==========================================
- Coverage   80.84%   71.41%   -9.43%     
==========================================
  Files           7       25      +18     
  Lines        1117     2571    +1454     
==========================================
+ Hits          903     1836     +933     
- Misses        214      735     +521     

Impacted Files	Coverage Δ
traja/models/manifold.py	0.00% <0.00%> (ø)
traja/models/visualizer.py	0.00% <0.00%> (ø)
traja/models/inference.py	31.81% <31.81%> (ø)
traja/plotting.py	56.50% <33.94%> (-13.44%)	:arrow_down:
traja/models/generative_models/vaegan.py	38.46% <38.46%> (ø)
traja/models/predictive_models/irl.py	38.46% <38.46%> (ø)
traja/accessor.py	66.66% <38.63%> (-16.07%)	:arrow_down:
traja/trajectory.py	80.62% <64.55%> (-9.42%)	:arrow_down:
traja/models/utils.py	72.50% <72.50%> (ø)
traja/frame.py	85.71% <76.19%> (-6.74%)	:arrow_down:
... and 31 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 756b792...494b39d. Read the comment docs.

[WolfByttner]

@justinshenk any idea why code coverage dropped like a rock? The changes are not that extensive.