FIX fix_annot_names():  only modify file if any names are different from clean file

When a morphed PALS_B12_Lobes was modified it was broken afterwards; might be
related to PALS_B12_Lobes containing names that are not associated with any
vertices?
DOC MneExperiment:  error for missing FreeSurfer
FIX MneExperiment:  allow parc=“lobes”
FIX MneExperiment.make_annot():  Don’t try to make parc=“”
FIX MneExperiment.make_annot() for ”lobes”:  provide subjects_dir
FIX MneExperiment.make_evoked():  epoch with sel_epoch

check modification date of proper rej-file
WIP GUI:  new backend App
WIP GUI:  incorporate SelectEpochs GUI
WIP GUI:  auto-run
WIP GUI:  disable toolbar “help” button
DOC GUI:  notes on controlling the GUI App
ENH plot:  `frame` argument for plot.UTSStat() and plot.uv
DOC plot
WIP _mne:  combine_source_spaces()