Fix some DeprecationWarning

[xoolive]

Following discussion #414 (comment)

There is still one DeprecationWarning to fix in traittypes.Dataset (dtype should be set in a tag() method)

[martinRenou]

Concerning the Dataset trait, I wonder if you could not simply remove the dtype tag, it's set to its default value (None) anyway.

[martinRenou]

Thanks a lot for the PR !!

[xoolive]

I think it should be enough to remove it but in the traittypes package

[martinRenou]

I think it should be enough to remove it but in the traittypes package

Well, dtype seems to be used in the traittypes package, only we set it to None because I guess we don't want to force the user to use a specific dtype. I suppose removing it from ipyleaflet is just fine.

[xoolive]

Well, I can't say: maybe it's fine, but it doesn't fix the warning 😞

[martinRenou]

I don't have those warnings... Which traitlets version are you using?

[xoolive]

traitlets==4.3.2

But I don't get the warnings on a regular import, only when imported through an entry point:

# something along
for entry_point in pkg_resources.iter_entry_points("personal.stuff"):
    entry_point.load()

[martinRenou]

I can merge this one as it is right now as it fixes some more warnings.

Thanks a lot for this PR! :)
I'll investigate concerning this Dataset thing

[xoolive]

Thanks, about the extra warning, see jupyter-widgets/traittypes#41

[martinRenou]

Good!! :) Thanks very much