decorator
Accepted a patch from Sylvain Marie (https://github.com/smarie): now the decorator module can decorate generator functions by preserving their being generator functions. Set python_requires='>=2.6, !=3.0.*, !=3.1.*'
in setup.py, as suggested by https://github.com/hugovk.
Avoided some deprecation warnings appearing when running the tests with Python 3.7.
Better decorator factories
Fixed regression breaking IPython