+ Renamed ee_color() to ee_set_color(), wrote ee_get_color().
  * libee/line.c:
    + Implemented draw_polyline() and draw_thin_polyline().
  * libee/sprite.c:
    + Removed the f member of struct ee_sprite.
    + Implemented ee_get_sprite_{width|height|dx|dy}().
    + Restore the color fater ee_draw_sprite() is called.
  * libee/box.c:
    + Fixed a bug causing improper box clipping at the right and the bottom.
  * data/foo_fighter:
    + Fixed bugs in the sprite.
  * src/intro.c:
    + Test effects for the future game's intro.
  * test/spritedit.c:
    + Added stuff to the sprite editor. We can now navigate through frames.

+ More robust sprite loader.
    + Added ee_set_sprite_frame() and ee_get_sprite_frame().
    + Free all structures in ee_free_sprite().
  * src/aliens.c src/bonus.c:
    + Use ee_draw_sprite() instead of our manual sprite rendering.
  * src/box.c:
    + Use ee_draw_line() instead of the manual equivalent.
  * data/:
    + Added foo_fighter, baz_fighter, item_gem and item_heart sprites.