enabled pixel smoothing

Rotating the sprite caused very noticable pixel jittering, so we enable
Texture Smoothing
started sector XML parsing, increased level size

Levels will now be stored as XML files, increasing modularity and making
it easier to quickly change levels without rebuilding the project and
changing code.
added DrawableGameObject for draw lists

This update allows us to create List<DrawableGameObject> that can
include all of our DrawableGameObject's such as Player, Starfield, and
other entities in the future