(c) Add support for VS 2012 in cmake launcher
(c) Do not include SDL.h

This inclusion was useless, and required to search for SDL library
in the CMake contained in the root directory
(c/libs) Replace SDL 1.2.14 by 1.2.15 (windows only)
(c) Simplify CMake files generated

- SDL-image is not required anymore
- For windows, both x86 and x64 versions of SDL are supported (fixed #12)
- include only required directories at the right place
- link to libraries is done only when it is mandatory
(c/libs) Remove SDL-image from libraries exported
(llvm/libs) Fix CMake files generated

Include headers before compiling libs and application