Generate ERFA wrapper automatically
Add jinja2 to .travis.yml
Only re-generate if needed
add option to silence cython_generator
Fix paths
Add preprocessing hooks
Make sure the hook gets run before sdist, add a fallback if jinja2 is not installed (as a backup plan in case timestamps from tar file get messed up and user doesn’t have jinja2), use importlib, and fixed package_data
Added mention of jinja2
Added note about jinja2 in changelog [ci skip]
Merge pull request #3166 from astrofrog/auto-generate

Generate ERFA wrappers (with modifications to astropy-helpers)