Put dotnet.exe into PATH

[forki]

It would be nice to have a simple way to put the dotnet path into PATH since tools like fable are calling into dotnet and need the correct version. /cc @alfonsogarciacaro

let dotnetTool = (install.Value (DotNet.Options.Create())).DotNetCliPath
let dotnetFolder = FileInfo(dotnetTool).Directory.FullName
Environment.setEnvironVar "PATH" (dotnetFolder + ";" + Environment.environVar "PATH")

[alfonsogarciacaro]

Yes, Fable is still relying on dotnet being globally accessible. Also remember we had trouble before with Windows and Unix systems (Windows uses ; as PATH separator, while Unix uses :).