Changes graphics library to SFML and adds some basic boilerplate code to MainGame.
Updates gitignore to ignore photoshop files.
Adds a basic tile map class and a MathHelper class to the Core project.
Adds a texture manager to the GUI project, along with a very basic tilemap.
Adds a noise utility class to the GUI project.
Adds the screen manager/screen classes (adapted from the MSDN article).
Fixes up the csproj file and some style issues.
Adds some emptyish interfaces for some managers.
Fixes the rest of the dependencies for the rest of the managers and moved the interfaces to their own folder.