organizing stimuli by user

Each person is going to want to manage their stims in different ways. As
cool as it would be to make one canonical Grating Stim that everyone
would use, it's impossible: people use different experimental setups,
different animals, and have different ideas about how stimuli should be
organized and should work.

So, everybody gets their own dir! Hopefully this will encourage
contribution, sharing, and organization, without limiting anyone's
creativity.