This way, we don't need to tell everyone who uses the enhanced branch
that they need to copy res/data_en. It also gives the CMake project a
way to bundle everything into a neat little folder.
For those not in the know, Visual Studio 2003 was what Pixel used to
compile Cave Story. Getting this to compile in its original environment
goes a long way to ensuring this decompilation's accuracy, since it
allows us to check if the code creates the exact same assembly.
Since the decompilation doesn't include the original DirectX/WinAPI
backends yet, compatible SDL2 and Freetype .lib files are provided.
