Create ScreenManager

Manages the non-gameplay screens (i.e. the Main Menu and anything else we may add later on, such as a pause screen)
Create GameScreen

A (mostly virtual) class with all the methods for screens other than the main game.
Create MainMenuScreen

The actual screen for the Main Menu itself.
Update Game1.cs

Cleaned out some extraneous code (I'm keeping this update separate from when I add the changes for the Main Menu, just to keep things a little cleaner and easier to track)
Main Menu Update

Implements the ScreenManager that allows separate screens such as the Main Menu to run. This includes some goto's in the Update and Draw methods to ensure that the main game does not change while the main menu is still up.
Update MainMenuScreen

Fixed a minor glitch where scrolling through the menu options tended to be kind of spazzy (a light tap would make it loop like a bazillion times in one second)
Consolidating some sprite names

Whoops! I missed some differences in the sprite names that kept the program from running. (There was still some references to the player as "ship"). I've decided to favor the newer "player.Sprite" that I used in my own program (where the texture is loaded as a part of the player class instead of in the Game class, making it easier if we want to change later) but if that interferes with other people's code, it's just as subject to change.
Game1 Overhaul
Character Overhaul
Player Overhaul
UserInterface Overhaul
Merge pull request #3 from crimsonKangaroo/master

Main Menu Update