ENH fmtxt:  Cache complete report

Allow creating the whole report without saving any file to disk
DOC fmtxt
ENH fmtxt:  add TOC to HTML Report
ENH fmtxt:  for HTML output, add Table cellpadding
FIX Interaction:  indexing with slices
ENH _ClusterDist:  add stars column
FIX _t_1samp():  splitting for large arrays
ENH MneExperiment.show_subjects():  add count and mri columns
ENH MneExperiment.show_subjects():  use current group instead of parameter; add caption
ENH Experiment.show_state():  add `hide` parameter
FIX MneExperiment:  stc_ndvar call
ENH/API MneExperiment.add_epoch_stc()

- add option for source space baseline correction
- make etc NDVar name consistent between evoked and epochs
API MneExperiment:  .add_evoked_label() —> .add_stc_label(), handle epochs as well as evoked datasets
ENH MneExperiment.add_evoked_stc():  when morph is requested and all subjects are common_brain, don’t morph
ENH MneExperiment:  add epoch parameter `sub`
FIX MneExperiment.iter():  only include subjects in the current `group`
ENH MneExperiment:  make _derived_labels an attribute
STY:  plot.uts
EXA:  print table with clusters
WIP MneExperiment:  PySurfer handling