Handle MSVC++ x64
remove the msvc directory in order to create a git module instead
Added submodule with MSVC++ 2012 prebuilt libraries

A submodule used instead of direct way of putting files into a repository
so that the official repo won't grow too much in size and since MSVC++
dependencies are not typically needed (on Linux/Mac and Windows with MinGW).

For those who don't need MSVC++ libs, they should just ignore the submodule.

Those who'd like to play with MSVC++ build should invoke:

git submodule init
git submodule update