As these files don't need to contain references to the source files,
although typically do, added basic files which only include three
filters and don't require the project file generator to be modified.
These files allow the source code to be viewed in the Solution Explorer
in versions of Visual Studio from 2010 onwards in the same manner as
previous versions did rather than one large view of files.
Carrying on from commit 11025613b9 added VC10 project files which are
capable of supporting side-by-side compilation, 32-bit and 64-bit
builds as well as support for some of the third-party libraries curl
uses.
