v0.12.0

Split narrow multi-dim numpy/HDF5 arrays into individually plottable columns, using generic column_N names when there's no real name to use (numpy files have no attribute mechanism at all, unlike HDF5). Applies whenever a multi-dim array's last axis is 20 entries or narrower and doesn't already qualify for HDF5's named-feature split -- wider arrays (e.g. embeddings) still flatten as before, since that's presumed to be genuinely homogeneous data.

Reported and verified against a real file: a (6013910, 4) array held 4 distinct quantities (an integer-like ID and 3 spatial coordinates) that were previously flattened together into one meaningless combined histogram; now each is its own selectable, plottable column_0..column_3.