Added Player

Player has been added to the game.
- Player is a flxsprite object that is currently just a red box.
- Player can move left and right relatively quickly.
- Player will run off screen. That will be worked on.
Player Code Cleanup

Various cleanup mods.
-Added comments.
-Removed accidental y velocity variable.
-Added variables for player height and width for cleanliness.
Will try to be better about committing shit, sorry.