Support for virtual environments
Many package managers and programming languages support the use of virtual environments to separate different versions of the same library used in different projects. Wouldn't Nim/Nimble need a way to create virtual environments as well? 

I'm new to Nim, and I've tried to look through the documentation of both Nim and Nimble, and I've searched the issues for Nimble on Github, but i cannot find any statement confirming that you either already support virtual environments or any explanations for why they might not be needed in Nim (maybe you solved the problem in a different way).

Maybe this issue can serve to kick off a discussion about Virtual Environments if it's not already implemented or otherwise unnecessary.