Changing how the game handles different screens.

Instead of changing both width/height, only changes width such that
viewport in same aspect as target. Thus, GL handles upscale/downscale.

Signed-off-by: Ken Hoover <ken.hoover@mail.utoronto.ca>
Padded cutting texture to POT. Reduced font texture size.

Signed-off-by: Ken Hoover <ken.hoover@mail.utoronto.ca>
Finished migrating UI to non-table format.

Some changes in GameScreen to compensate. Added the front stage's
background.

Signed-off-by: Ken Hoover <ken.hoover@mail.utoronto.ca>