Hello!
First of, thank you for creating this awesome package. It solved some major headaches for me.
May I suggest an improvement to WithReferenceAssembleis extension method?
Currently, it is implemented as compilation.WithReferences(...) which replaces everything one might have provided during compilation creation. Would it be better to replace it with compilation.AddReferences() which does preserve the existing references?
If the idea sounds good, I can submit a PR to the effect.