update .mailmap file
Introduce Utils::loadGraphicSurface to load images.

The function being introduced replaces a pattern which is found all over
code base:

	image = IMG_Load(mods->locate(filename).c_str());
	if(!image) {
		fprintf(stderr, "Couldn't load image: %s\n", IMG_GetError());
	} else {
		// optimize
		SDL_Surface *cleanup = image;
		image = SDL_DisplayFormatAlpha(image);
		SDL_FreeSurface(cleanup);
	}
Add options to loadGraphicSurface and use it more often
Use the loadGraphicsSurface in Tileset, ImageManager, GameStateLoad.