Build: Add Build Support for Visual Studio 2013

Like the Visual Studio 2012 projects, the Visual Studio 2013 project files
are only slightly different from the Visual Studio 2010 files, in more or
less the same manner.  We can thus easily provide out-of-box support for
building under Visual Studio 2013 by expanding on the scripts used to
provide support for the Visual Studio 2012 projects, without adding much
maintainance overhead.