symbolic link storage option support

[cboudereau]

Description

In order to reduce time + disk space of the packages folder, an option storage: symlink could link the nuget cache dir to the package folder (inside the packages folder).

I have done the dev in my fork and I am building integration test (I need an issue number to name scenarios).

[cboudereau]

Could you assign me the issue please ?

[matthid]

thanks for looking into that :)

[matthid]

Just a word of warning: Keep in mind that we have not done this yet because a lot of devils lie in the details (xplat for example is one of those devils ;) )

[cboudereau]

done #3128