STY save._pickle
FIX ui.tk_ui:  ask_saveas
API testnd:  use **sub to access partial permutation distribution
FIX testnd.anova:  add .compute_probability_map() method
ENH data-obj:  ADD Categorial dimension
API:  make Var.index() consistent with Factor.index()
ENH testnd:  collect distribution for parcellation
WIP mne API Label.fill()
ENH load_test:  proper test caching for parc and tf-tests
WIP MneExperiment:  make report for threshold-free permutation tests