Added art, fixed jump, fixed object placements

-Added Jen's platform sprites
-Fixed jumping
-All of the game objects in Level 2 were placed at -6.2 Y and -4 Z for
no reason, not sure why. Inconsistent with other levels - everything in
every level is now at -1 Z, and the player starts at 0 Y (with all other
objects placed based on player's coordinates)