Import submodules into __init__.py for IDE code completion

[alysivji]

Fix for #144, but only for the dash library itself.

I was also looking to add IDE completion for dash-core-components, but this seems a bit more difficult as component data is loaded from metadata.json.

import dash_core_components as dcc
print(dir(dcc))

We see all the core components in the namespace (and, therefore, in IPython), but they do not show up in the IDE. Hardcoding __all__ is a workaround, but not something I want to do.

@chriddyp do you have any thoughts on this?

[chriddyp]

let's leave this one out, as it isn't used anymore (dash-auth package is used instead)

[alysivji]

Fixed!

[chriddyp]

This looks good to me. Is this syntax safe for python 2 and python 3? Tests passed, so I'm assuming that it is.

[chriddyp]

IDE completion for the component libraries will probably require doing code generation/builds rather than dynamic code evaulation at runtime. This was started in #150, I'll continue the discussion over there.

[chriddyp]

I was also looking to add IDE completion for dash-core-components, but this seems a bit more difficult as component data is loaded from metadata.json.

I've added some comments about what would be required to do this here: #150 (comment)

[alysivji]

Relative imports work in both Python 2 and 3. Looks like they were introduced in Python2.5 via PEP 328.

Thanks for the detailed writeup on how to add IDE completion for components. I will take a look when I get some time.

[chriddyp]

Thanks @alysivji !