[fixed] LWJGL not having Gdx.gl* set.
[changed] Bunch of code to use Gdx.gl* rather than getGL*().
[changed] gdx-twl uses SpriteBatch for images. TextAreaTest is still fubar.
[fixed] gdx-twl uses the flipped y-coordinate system TWL expects.
[added] Method to SpriteBatch that takes precomputed tex coords and color. SpriteBatch methods need clean up?
[changed] BitmapFont computes glyph tex coords up front and supports being used with a flipped y-coordinate system.
[added] BitmapFontFlipTest to test flipped y-coordinate system.
[added] getColor to Sprite.