changed global animations to handle only one CE change event per frame

changed global animations to handle only one CE change event per frame

Before, several (same) CEs could change within the same game frame,
triggering the same global animation several times (each time with the
new/next CE, with different CE position for each change. for example).

This bugfix results in each global animation being triggered exactly
one time for each change of the same CE in the same frame (which is
especially important if there are several global animations being
triggered by the change of the same CE, to display several animations
for several same CEs changing in the same game frame).