Stuff exported with __all__ variable should be always public

[tristanlatr]

Names re-exported by the __all__ variables are public names in Python, even starting with an underscore. To make the submodule _igraph public, just re-rexport it in igraph package in the __all__ variable.

We do not currently support that.

An issue with that approach (that should be supported anyway) is that all public names must be added to the __all__ variable unless python will not import your names when doing a wildcard import.

[tristanlatr]

Does it mean that the names that are not part of the __all__ variable should be considered private ? This would be a breaking change, so I don’t think so.