Final Updates Pre 7DRL

Added some more polish, there are a few more features that I might get around to adding, but most likely those will be saved for a sequel.

• Added a main menu with a credits screen
• Added a scoring system, with different messages depending on how well you do
• Added a wall of force around the map

I wanted to get this out before the next 7-Day Roguelike Challenge, which starts 2/29.  I'll be creating another game then, but I'll still fix bugs on this one, should you find any, so comment on this post (or the main page) if something comes up.