Image buffer display in the animation player was difficult to reason
about because it could potentially access the entire play-state on load
(frame-step, modifier keys... etc) even though these are are only
intended to be used interactively.
Add playanim_toscreen_ex which is called by both
playanim_toscreen & playanim_toscreen_on_load which doesn't use the
PlayState struct.
4f3e2ee857