fixed bug with global animation at wrong playfield position for one frame

This fixes a bug that should have been fixed with commit 03202ac7.

While the above commit fixes the problem for some cases, it still does
not work correctly if a global animation with ".position: ce" has two
"ce_change" events defined with ".init_event" and ".anim_event". While
the first one starts the animation (and should therefore place the
animation at the CE position), the second one stops the animation (and
starts the next part of the animation, if existing), so it should not
change the position to the second CE (which would only be used for one
single game frame and then changed to the animation position defined
by the next part of the animation).