Reset some stats that weren't being reset in deletestats

This function now properly deletes the Super Gravitron record, the Super
Gravitron rank, and the best game deaths. They were not being properly
reset previously, meaning you would have to go into your save file to
properly clean out your save data.

desktop_version/src/Game.cpp

@@ -3986,6 +3986,9 @@ void Game::deletestats(void)
             bestlives[i] = -1;
             bestrank[i] = -1;
         }
+        swnrecord = 0;
+        swnbestrank = 0;
+        bestgamedeaths = 0;
 #ifndef MAKEANDPLAY
         graphics.setflipmode = false;
 #endif