Pushes the check_dims arg down.
Merge pull request #18 from t3on/tb-combine-ENH

FIX combine():  push the check_dims arg to nested calls.
ENH MneExperiment src:  add distances
FIX MneExperiment:  get("x-dir", make=True) creates directory
MOD MneExperiment:  don't set_env() on __init__
UPDATE MneExperiment:  use new epoch selection GUI
FIX unpack_epochs_arg():  use asndvar(), allow Xax='case'
ENH _mne:  add `labels_from_clusters()`
ENH _mne:  source_induce_power()
ENH _mne:  add morph_source_space()
ENH NDVar repr:  leaner __repr__, new .diminfo()
FIX NDVar:  UTS indexing error message
ENH NDVar:  Scalar indexing allow close value match
ENH MneExperiment:  load_evoked_freq()
ENH MneExperiment movie: allow p0=0.1
ENH MneExperiment:  `all!` group
FIX MneExperiment:  `src-file` pattern needs to include "{src}"
ENH:  support volume source spaces
WIP ENH testnd:  test repr (add mintime etc.)
OPT stats:  _t_rel