ENH fmtxt:  add paragraph
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
ENH ClusterDist.clusters():  add p_parc corrected across parc
ENH MneExperiment.load_test():  proper test caching for parc and tf-tests
ENH MneExperiment.load_test():  add mask parameter
WIP MneExperiment:  make report for threshold-free permutation tests
WIP mne API Label.fill()