Allow linking packages that have arbitrary contents in the 'lib' folder.

[felix-b]

Currently, package 'lib' folder must be result of compiling a single project (e.g. automatic packaging of project on build). Packages with arbitrary contents of 'lib' achieved with manually authored .nuspec are not supported.

[jakst]

Is this the cause of the below error message?

Fatal error: Error: Cannot link package My.Package: 'lib' folder not found, 
expected ~/.nuget/packages/my.package/1.0.0/lib

I wanna link a local package that I have the source code to, but I do not have access to the original nuget feed. I've run dotnet restore, dotnet build, and dotnet publish on the package source project, but it never end up in my .nuget/packages folder.

I'm on mac, and my `.nuget/packages/ folder only seems to contain nugets that I've fetched from a remote feed.

[felix-b]

@jakst, thanks for using NuLink! your issue is tracked by #12 (Allow linking unpushed packages).