Explicit positioning and cropped output

[Aaron Hill]

Using -dcrop to generated cropped output breaks explicit positioning of 
systems/staves.

%%%%
\version "2.19.82"
\layout { indent = 0 }
<<
  \new Staff \repeat unfold 6 b'1

  \new Staff <<
    \new Voice {
      s1*2 \break
      \overrideProperty 
Score.NonMusicalPaperColumn.line-break-system-details
        #'((extra-offset . (5 . 5)))
      s1*2 \break
      s1*2 \break
    }

    \new Voice \repeat unfold 24 b'4
  >>

  \new Staff \repeat unfold 12 b'2
> >
%%%%

When rendered normally, the middle system is properly offset.  When 
using -dcrop, no offset occurs.


-- Aaron Hill