Allow debugging multiple projects in one debug session

_From @matthewrk on June 23, 2016 13:22_

This problem specifically affects dot net core development via vscode. I'm not entirely sure if its a core problem or a vscode problem. Apologies if this issue is misplaced.

The global.json file allows you to define sub projects, similar to a solution in vs.net. A very common setup for a .net project is a web app with several class libraries. This is achievable in vscode and everything works brilliantly until you attempt to debug.

It doesn't seem possible in vscode currently to debug a web app under this setup (problems locating source code due to limitations in conf files), or to place breakpoints within the web app itself as well as class libraries to follow execution when debugging.

This seems like a pretty critical requirement for any mid-large sized project, and is a hurdle to being able to migrate to using vscode for projects (on a mac, in my case) from vs.net.

I have been discussing this problem on stack overflow looking for possible solutions:
http://stackoverflow.com/questions/37376415/debugging-in-vscode-with-multiple-dotnet-core-projects-under-one-solution

And also in the comments here on a blog post about setting up multiple projects under one roof in vscode:
http://forums.dotnetfoundation.org/t/referencing-another-project-in-net-core/1298/9

Where you can find more information on my attempts to achieve this functionality should it be helpful.

_Copied from original issue: Microsoft/vscode#8052_