keep-inside-line doesn't adjust for long marks

[Jay Anderson]

This would be nice to have, but it's not a huge problem. At the very least
perhaps a comment should be added to section "5.7 Avoiding tweaks with slower
processing" which states that keep-inside-line doesn't affect marks.

Thanks for the great work!

-----Jay Anderson

\version "2.11.34"

\score
{
  \new Staff \relative c'
  {
    \time 4/4
    \override Score.PaperColumn #'keep-inside-line = ##t
    \repeat unfold 9 { c1 }

    %This one is fixed
    c1_\markup{A Long Markup Which Goes Off The Page}
    \repeat unfold 8 { c1 }

    %This mark still goes off the page.
    \mark "A Long Mark Goes Way Off The Page"
    \repeat unfold 12 { c1 }
  }
}