Massive texture update!

* Replaced nearly all existing sprite textures
* Added TextureUtil and TextureFormatException classes
* Modified texture processing and animation for many concrete sprites
* Changed Man to Engineer
* Added relevant states to several concrete entities (tank moving,
engineer building, etc.)
* Created several Sprites that were missing, and updated Sprite tests to
use non-mock entities (Rubble, etc.)
* Created Effect class, moved Bullet there, along with new MineExplosion
and GenericExplosion
* Modified Drawlayer entries