Use msbuild instead of devenv in makefiles

[maelh]

Msbuild clutters the output with a lot of messages, and works slightly differently, which is why I kept the use of devenv.exe for now.

But switching eventually is a good idea, as msbuild deals better with usernames that have non-ASCII characters in it (devenv.exe will fail with strange error messages with such user names -- tracking that was the cause took a while).