Organize game files

I moved all the files (except for toadman3.bas) in the root folder into
a new "game folder. This folder is to hold files related to game logic.

I also created a Game_Session class to hold all of the objects and
properties of the game currently in play.
Update title and game background
Update Level 2
Add message popups for flamethrower, jump boots, and blue flame

* Needed to tell player what they just got and how to use it