GDP: fixing cropping

[Graham Percival]

In the past few months, whenever anybody said that an example
was cropped too much in the output, I said "it's already noted as
bug 268, so just bear with it".

The initial example with 268 was fixed, but I'm certain there's
still examples left.  GDP people: please check your sections in
the **GDP OUTPUT**.  (this uses the latest lilypond version, so
bugfixes should be fixed on there)

If you see something cropped too much, please create a minimal
example and add it to issue 268.


Also, could somebody investigate this?  I'm /fairly/ certain that
the slur in this example gets cropped a few pixels too much, but
it would be nice if we had a way to be sure:  (other than "the
bottom of the slur looks too flat, and it's right next to the png
boundary"... unless the -dpreview box is *supposed* to have at
least one pixel of whitespace around everything.  Personally, I
think that would be a good way to test it... but this might get
into weirdness about pdf->png translation)

{
  c'( c')
}

Cheers,
- Graham