Add _axes_display_names argument to the dump() method

[alixdamman]

The dump() of the Array class uses the AxisCollection.display_names property to generate the axes names. This means that exporting arrays with anonymous axes will convert the None names as strings {i}*.

However, I am not sure it's worth it to add a new argument to the dump() method.

@gdementen
What do you think?

[gdementen]

Honestly, I fail to see a case where a user would want {i}* instead of nothing at all (an empty string!) in an Excel file.

Do you think using .names in .dump instead of .display_names would break anything? If not, I think that's better than adding yet another option that nobody will ever use.

[gdementen]

My former self probably found it elegant to have Excel tables, CSV files and the string representation of arrays as similar as possible, but my current self disagrees 😉.

[alixdamman]

Well, dump() is used by Array.__str__(). So we really need an extra argument but we can choose to define axes_names as self.axes.names by default and self.axes.display_names otherwise.

[gdementen]

Yes, indeed. Maybe a private argument name (_axes_display_names=False)?

[alixdamman]

Good idea.