Minor cmake issue
As a quick warning to anyone who might be looking at the VectorStorm codebase, as of cmake version 2.8.10 (or thereabouts), the variables describing where to find SDL_mixer and SDL_image have changed from SDLMIXER_* and SDLIMAGE_* to SDL_MIXER_* and SDL_IMAGE_*, respectively. Which caused me a good fifteen minutes of confusion before I was able to…