Identify typing.NewType wrappers and construct annotation references

[gwax]

Resolves #41 producing output of the form NewType(NewName, OldType) with appropriate references.

[rmorshea]

@gwax @agronholm any idea whether this will get merged in? This would be super useful to me.

[agronholm]

I'll try to take a look at this this weekend.

[agronholm]

Thanks!

[agronholm]

@gwax I've been rechecking the code and I cannot figure out why you chose to format the name of the NewType as :py:data:~TypeName. Shouldn't it contain the module name as well, like :py:data:~module.name.TypeName? I'm also wondering if the formatting scheme is even in the right direction. Maybe just :py:data:~module.name.TypeName should be used, without involving typing.NewType?

[agronholm]

Ok, the module name containing the new type is not recorded anywhere so this is the best we can do. Sorry for the noise :)