Changed CSS so animations don't 'rewind'

They stay on the last frame. Otherwise classes like
toontalk-bird-fly-down flash the first frame before switching to the
next state.
Improved Bammer animation

Also animate_to_absolute_position now resets the transition-duration.
Show improved the bird hatch animation

And also no longer allow the bird to go 'off screen'. And waiting bird
is just an image.
Birds can fly in 8 directions