Create a Level Number Texture

Rather than having the level number be generated from the font file for the outline, there should be a texture with the numbers in it to allow for more customization of the GUI in resource packs. Packs that increase the resolution of the font also don't work very well with the way the outline is generated, causing it to look incorrect. Making them into separate textures would also allow the level numbers to be stylized differently than the font of the rest of the game.