ENH testnd:  duration based cluster correction
ENH mne_experiment:  add .next() method to move through field values
ENH mne_experiment:  more rejection options

- use `kind` entry as primary option
- allow "make" (made by the user but not with rejection GUI)
STY mne_experiment.list_files()
ENH mne_experiment:  add .make_raw() with some defaults
FIX SelectEpochs:  remove bad sensors from mean seg
ENH mne_experiment.make_epoch_selection():  automatically specify mad channels
ENH mne_experiment:  add make option to .get()
FIX/ENH SelectEpochs:  layout;  nplots arg, DOC
ENH SelectEpochs:  disable next/back buttons at extreme pages
FIX mne_experiment:  test name should include cov
FIX colorspaces:  pickle without matplotlib colormap
FIX ndvar:  add .shape attr
ENH wxterm:  app look for Debug in config;  implement MacReopenApp().
AMD cs
ENH plot ndvar:  add Xax and ds arg to all plotting functions
FIX wxterm:  py-editor suggestions popup
ENH Sensor dim:  add x, y and z properties
FIX dataset.save_txt():  header=False
FIX mne_exp ttest