Implement regular array support for TClonesArray

[nsmith-]

No description provided.

[nsmith-]

The test will require merging scikit-hep/scikit-hep-testdata#65

[nsmith-]

This will have issues with delphes_tree["GenJet04/GenJet04.Constituents"].array(library="np") once #441 is merged, need to look a bit more

[jpivarski]

The test will require merging scikit-hep/scikit-hep-testdata#65

See

https://github.com/scikit-hep/scikit-hep-testdata/actions/runs/1247612638

to file the progress of releasing 0.4.8.

[jpivarski]

And ping me again when you're ready for this to be merged. (The changes so far look good.)

[lgray]

@jpivarski that CI run failed looking at the link!

[nsmith-]

Actually the problem was much more subtle: essentially by chance the data was such that numpy converted a list of TRefArrays with the same number of refs into a 2D array. This is because by default:

>>> numpy.array([ [1,2], [3,4] ], dtype=object)
array([[1, 2],
       [3, 4]], dtype=object)

[nsmith-]

@jpivarski this is ready