add an ability to find the import string for constants and typedefs

[chrisdonlan]

Currently, if I set up a constant or typedef:

constant = 'foo'

Label = str

Then when I query for the import string with the constant or typedef's value, the getimport function will not work (of course):

dill.source.getimport(constant) 

This is a meaningless request, because dill.source.getimport(constant) will look at the value of constant to determine the import, which is a string, 'foo'.

In order to support the look-up of typedefs and constants' import paths, something different would need to be attempted, likely involving reflection.

[chrisdonlan]

I was able to get around this with some logic. Might be worth looking into though. Closing.