Revamp interfaces. Cameras are now private, and must be passed to
GameScreens on render. Objects farther down the hierarchy just take the
final transformation matrix, which the screen must prepare for them.
This gives the screen more control over where and how objects it manages
are drawn. Fix top-level render method to call initialize on the very
first GameScreen to allow resource creation not possible prior to that
point. Add ProgressBar and Updatable interfaces for organizational
purposes. Reorganize packages. Minor adjustments to mmd.png. Change
first map of SeeteufelScreen to use orthographic projection. Minor
updates to design of same map. General cleanup.