Page and line penalties

[Joe Neeman]

As far as I can tell, page and line penalties are used _only_ for forbidding 
and forcing page breaks. Is there much chance they will ever be used for 
anything else? If not, they could be replaced by booleans - this would make 
the breaking algorithms a bit easier.

Also, there seems to be some confusion as to where the line break penalties 
are used. Paper_column_engraver interprets the penalty as a boolean anyway 
(when it is over 10000).

Of course, page turn penalties would need to be introduced because we (will) 
make a distinction between allowable and desirable page turns.

Joe