index.html: Adds resources section Game Mechanic Explorer.
Started to add game mode support (menu, start, end, etc), but I left it broken for too long without looking at it and I forgot what I was doing, so I don't know how to fix it. Committing so that I can revert to a version that works.
New baddie/bomb and missile images. Stronger gravity.
New city and bomb sprites. Adds FPS display.