Add __pycache__, _build, and *.pkl to .gitignore

Add pycache, _build, and *.pkl to .gitignore
e95e7736 · Brandon T. Willard · Thomas Wiecki · 150add2c · e95e7736
--- a/.gitignore
+++ b/.gitignore
+*.pkl
+_build
+__pycache__
 .coverage
 *.linkinfo
 *.o