ENH:  support volume source spaces
ENH testnd:  test repr
OPT stats:  _t_rel
ENH testnd:  ADD t-contrast
OPT _t_rel:  use data buffer
OPT _Effect.sort_idx()
ENH Interaction: as_effects -> LazyProperty
ENH fmtxt HTML:  embed images
FIX TreeModel:  repr without initial state
API MneExperiment:  load_evoked_stc default sns_baseline to (None, 0)
ENH plot.brain:  ADD copy()
FIX plot.brain:  colorbar and time_label
ENH plot.brain:  ADD bin_table()
ENH fmtxt:  Section.add_image_figure() with Image object
ENH datasets.get_rand():  make seeding optional
API eelbrain.lab:  don't import plot.coreg
FIX plot.Array:  non-adjacent y dimensions
FIX plot.Array:  ticks
FIX plot:  layout
API cluster tests:  default pmin=0.05