ENH asndvar():  handle lists of mne Evoked objects
ENH Celltable:  coercion parameter
ENH tested tests:  add tail to repr
STY:  remove __hide__
FIX WxTerm:  don't use class variables on Shell
UPDATE MneExperiment:  use new epoch selection GUI
FIX unpack_epochs_arg():  use asndvar(), allow Xax='case'
ENH MneExperiment:  allow setting excluded values