Issue 3942: Scale slurs and ties when using \magnifyMusic. (issue 103890046)

[markpolesky]

Reviewers: ,

Message:
Please review this new patch.  I'm not entirely sure this is the right
approach, so I may need some advice here.

Thank you!
- Mark

Description:
This is a (possibly misguided) attempt to get slurs and ties to scale
properly when using \magnifyMusic.  For the most part, I've just copied
the appropriate grob-properties from Slur, PhrasingSlur, and Tie, and
scaled them to the magnification value.  The results are, well, mixed.
I posted some images here:
http://code.google.com/p/lilypond/issues/detail?id=3942

Also, I feel that there *must* be a more elegant way of doing this, but
I can't figure it out.  Any help is appreciated.

Please review this at https://codereview.appspot.com/103890046/

Affected files (+188, -6 lines):
  A input/regression/magnifyMusic-phrasing-slurs.ly
  A input/regression/magnifyMusic-slurs.ly
  M input/regression/magnifyMusic-stem-beam-spacing.ly
  A input/regression/magnifyMusic-ties.ly
  M ly/music-functions-init.ly