Consolidating LayoutManager's and AbstractBreaker's getNextKnuthElements() methods

[Glen Mazza]

Jeremias, perhaps Luca:

Is there a reason why we maintain separate getNextKnuthElement() methods 
within both an LayoutManager and its inner AbstractBreaker?  Can they be 
consolidated into LayoutManager and we call 
getTopLevelLM().getNextKnuthElement() instead within the breaker code?

Three LM classes have these two "duplicate" methods:  PSLM, SCLM, and 
BlockContainerLayoutManager.  SCLM and BCLM I cannot tell if they are 
mergable--it looks doubtful to my eyes but I'm unsure, however PSLM's 
two implementations look somewhat strange:  for PSLM, what else would 
activate PSLM.gNKE() other than its PageBreaker.gNKE()?  If "nothing", 
those two should be merged at least to PSLM's implementation to clarify 
-- I'll happily do so if I'm correct here.

Thanks,
Glen