Clean up of code and more VS support

[Sarkie]

Hi,

1. I've moved vs stuff to its own folder and their own .sln for each version. (Need to do the same for vcproj maybe)
2. Added lib directories and read me, so they are none version specific
3. Updated .vcproj to compile with new .c file structure (I think)
4. Updated README.md to tell user of prerequisites
5. Added a build step to copy the sdl* .dlls to the bin directory

That's it I think. Sarkie.