FIX plot.Array:  non-adjacent y dimensions
FIX plot.Array:  ticks
FIX plot:  layout
API cluster tests:  default pmin=0.05
API ClusterDist:  threshold and tail instead of t_upper and t_lower
TEST ClusterDist:  non-adjacent ndim > 2 (BK)
FIX ClusterDist:  non-adjacent, ndim > 2
OPT ClusterDist
OPT ClusterDist:  pre-allocate memory buffers
ENH ClusterDist:  TFCE (Threshold-free cluster enhancement)
API testnd:  default pmin to None
WIP DOC _mne
ENH ClusterDist:  add trends to TFCE table
OPT ClusterDist:  cluster labeling
OPT ClusterDist:  cluster labeling (optimized connectivity representation)
AMD trend
API ClusterDist:  Only store cropped data
API:  RM clean_time_axis()
ENH ClusterDist:  find local maxima
ENH Dataset:  .add_empty_var()