How about source-level importing the third-party modules for D

[Heromyth]

In DUB repository, all the projects are avaliable in source. When 
my project depends on some of them, I want to import them in 
source level, instead of using them as some static libraries.

Of course, I can copy all the depended projects into my project 
and build it in source level.

So, is it possible to import the depended projects in source 
level whout copying them? Or, is it necessary for D to support 
this feature?

Thanks!