DUB 0.9.21 beta 1

[Atila Neves]

> It also supports setting a custom file containing main(), so 
> that for
> example custom unit test runners can be specified and similar


Awesome!

> things. In
> this case, the generated file looks like this:
> ---
> module test_main;
> import <library_name.main_module>;
> import <custom_main_module>;
> ---
>
> For packages with only executable configurations it behaves the 
> same as
> "dub run --build=unittest".

So custom_main_module defines the main function to be executed?