raise ValueError, not return ValueError
test error condition
don't check bad design matrix twice
test another bad design matrix condition
workaround for setuptools bug
refine workaround
improve style of pytest code
don't pickle dummy callbacks
change design kwarg to design_matrix
pass demo kwarg down the hierarchy
recursive yield froms aren't as flexible as I might have liked
use lists for Designs
improve docstring
fix typo
tests for experiment.py