* Fsi.exe should be called fsi.exe systematically. Let's normalize this now.
* Fsi.exe is always called fsiAnyCpu.exe on Mono. Although both are odd names, it's best to use the same as what is already used on case-sensitive file systems. Let's normalize this now.
* Fix dependencies in FSharp.Core nuget description to match project.json
* Simplify propagation of PREFERRED_UI_LANG define