FIX MneExperiment.add_evoked_stc():  make annot file
FIX plot.uv:  pairwise bars for many significances
FIX MneExperiment:  save box plots as *.png

Boxplots saved as SVG are not displayed correctly in Safari
FIX test.pairwise():  don’t make cell names bold
WIP EXA source_cluster