Reintroduce fullscreen support

The option was just ignored - parse it again to set
SDL_FULLSCREEN.

Previously the SDL_Quit() call was missing. This function should always
be called during shutdown independent of this commit, but in this case
it also resulted in the resolution not being reset on exit.

Also see issue #359.

src/display/graphics.cpp

@@ -38,6 +38,7 @@ LegacySurface *Graphics::legacyScreen()
 
 void Graphics::create(const std::string &title, bool fullscreen)
 {
+    uint32_t modeFlag = 0;
 
     if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) < 0) {
         throw std::runtime_error(SDL_GetError());
@@ -50,9 +51,11 @@ void Graphics::create(const std::string &title, bool fullscreen)
     //END:TODO
 
 
+    if (fullscreen) {
+        modeFlag = SDL_FULLSCREEN;
+    }
 
-
-    _display = SDL_SetVideoMode(WIDTH * SCALE, HEIGHT * SCALE, 24, 0);
+    _display = SDL_SetVideoMode(WIDTH * SCALE, HEIGHT * SCALE, 24, modeFlag);
 
     if (!_display) {
         throw std::runtime_error(SDL_GetError());
@@ -101,6 +104,8 @@ void Graphics::destroy()
     _scaledScreen = NULL;
     _screen = NULL;
     _display = NULL;
+
+    SDL_Quit();
 }
 
 void Graphics::setForegroundColor(char color)