Initial Commit

-Added explosion image
-Made a number of customizable setting variables
-Made some cheats
-Moved the settings out into a separate file (using YAML for ease of editing)
-Improved collision detection
-Improved missile firing system
-Added a score counter
-Made some small improvement and readability tweaks to the code nearly everywhere
-Included generated Documentation (by Pycco) for project
-Lastly (but perhaps most importantly): Everything is extremely well-commented!