IL merge Newtonsoft and minor output handling fix

[tpetricek]

If we do not IL merge Newtonsoft.Json.dll, then Vagabond (MBrace) breaks :-(

The issue was that Newtonsoft.Json.dll gets loaded from two different places (one that comes with FsInteractiveService and another that comes with FsLab, and Vagabond cannot resolve which one to use). Since this is exe, I think this is acceptable solution, though I'm not particularly happy with it.

[tpetricek]

Do not merge yet, looks like we'll need the same thing for Suave.dll

[tpetricek]

I like this even less than before, but ILRepack generates two FSharp.Core.dll references for different versions of it when I added Suave, so instead, this is using the same strategy as in: fsprojects/FAKE#1097. We create our private FsInteractiveService.Suave.dll, that does not clash with the normal one.

This is all ugly as hell, but I can finally run MBrace properly ☁️ ⛅ ☁️

[tpetricek]

Adding bug fix for an issue reported by @evelinag from NDC workshop. The PR #3 broke fsi.AddPrinter, which should now be fixed.