Update and deprecate top-level exports

[kjun9]

This removes (with deprecation) several of the re-exported names previously available at the top level of the stellargraph hierarchy. Specifically:

before	after
stellargraph.expected_calibration_error	stellargraph.calibration.expected_calibration_error
stellargraph.plot_reliability_diagram	stellargraph.calibration.plot_reliability_diagram
stellargraph.Ensemble	stellargraph.ensemble.Ensemble
stellargraph.BaggingEnsemble	stellargraph.ensemble.BaggingEnsemble
stellargraph.TemperatureCalibration	stellargraph.calibration.TemperatureCalibration
stellargraph.IsotonicCalibration	stellargraph.calibration.IsotonicCalibration

It also adds the remaining names to __all__, so that they're imported when one writes from stellargraph import * and thus that is consistent with the names that are accessible as stellargraph.foo (after import stellargraph).

See #714

[codeclimate]

Code Climate has analyzed commit 711a6de and detected 4 issues on this pull request.

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[huonw]

Looks good as is, but there's a question that may result in either follow up work or bigger changes here.

[kjun9]

@huonw

I've tried removing the other top-level exports and added the deprecation warnings like you suggested (but this also suffers from #1117 I'm guessing). I kept the classes from core as top level exports since core is not part of the top-level __all__ at all.

[huonw]

Looks good!

Could you update the PR title (or at least, the final commit message) to reference that it's also deprecating some of our top-level exports?

(For these things that are just changing imports, it's probably ok to just commit the code change by itself, without the rest of the slightly-different-randomness changes from rerunning the notebooks... as long as the notebook runs, of course.)

[huonw]

This looks good to me, and the warnings seem to appear in Jupyter at least 👍

It may be good to validate with @PantelisElinas, who added both the calibration (#326) and ensemble (#343) code.

[kjun9]

Hi @PantelisElinas I've added you as reviewer - for now this can wait in case you're available soon to check my assumption that the ensemble and calibration functions/classes don't need to be re-exported at the top-level, but I'll also eventually just go ahead with the merge if that's not the case.

[PantelisElinas]

It looks ok to me, if this is the way it should be.

P.

[kjun9]

if this is the way it should be.

Classes and functions in ensemble and calibration didn't particularly occur to me as something to be treated differently from things in other modules, so that's the motivation for removing them from the top-level so that we can be consistent now and in future, but not that there's a way it should be if that makes sense.

Thanks for taking a look!