[wix-devs] Linux changes

[Sean Hall]

We have a couple of PRs to start supporting Linux -
https://github.com/wixtoolset/Tools/pull/44 and
https://github.com/wixtoolset/Core/pull/165.

dotnet.exe does not support '/' for switches, even on Windows. Maybe we
should remove support for it as well?

v3 had a very complicated build system to try to support building WiX with
many different versions of VS. How flexible are we going to try to be in
v4? Are the OS conditioned changes that I proposed something we want to do?