grob creation

[Rune Zedeler]

Still struggling with the accidental engraver.
I still quite haven't understood the idea of the different functions in the 
engravers.
I tried moving all the code from "process_asknowledged_grobs" (or whatever name 
the function is changed to) to "stop_translation_timestep" - and (no surprise) 
it seems to be working.
The question is: Is it "bad" to create the grobs not until "stop translation 
timestep" - will this cause other sophisticated problems in other parts of lily?
Why is it that "process acked grobs" are called so many times instead of just 
one time after the processing of all grobs (i am talking about the loop in 
engraver_group_engraver)?

-Rune