[PATCH] Fix misalignment in DynamicTextSpanner (again :)

[Neil Puttock]

Hi everybody,

Please review this patch: http://codereview.appspot.com/186112/show

Following Joe's comments about my original patch
(http://lists.gnu.org/archive/html/lilypond-devel/2008-11/msg00380.html),
I considered making the 'bound-details changes in line-spanner.cc, but
have settled for a 'before-line-breaking callback instead; I believe
this is preferable to adding grob-specific code to the
line-spanner-interface.

BTW, this patch needs Marc's recent ly:grob-set-nested-property! patch to work.

Cheers,
Neil