fix repeat-sign problems introduced with issue 2533 (issue 6431044)

[benko . pal]

Reviewers: ,

Message:
patch enhanced to fix
http://code.google.com/p/lilypond/issues/detail?id=2648

if anyone wants to run regtests, please run both versions on the new
regtests.

I'd be happy to split the patch into several commits.

Description:
fix repeat-sign problems introduced with issue 2533

This reverts commit d05afb4c0bf29cbd6a98691c9c62afa1604fa4b2,
i.e. applies (a modified version of)
2a872121379fffe7b1cd5d23048b7ea04b4d1f68.
modifications relative to the latter are
- dot size is queried (not hardcoded) when printing a repeat sign
- bar line extent is shrunk not by scaling but cutting
- new regtests for repeat sign in exotic staves
  (non-default staff size, line count, line positions)

Please review this at http://codereview.appspot.com/6431044/

Affected files:
  M input/regression/ledger-lines-varying-staves.ly
  M input/regression/non-centered-bar-lines.ly
  A input/regression/repeat-sign-global-size-10.ly
  A input/regression/repeat-sign-global-size-30.ly
  A input/regression/repeat-sign-layout-size.ly
  A input/regression/repeat-sign.ly
  M input/regression/staff-ledger-positions.ly
  M input/regression/staff-line-positions.ly
  M input/regression/zero-staff-space.ly
  M lily/bar-line.cc
  M lily/beam.cc
  M lily/breathing-sign.cc
  M lily/custos.cc
  M lily/rest-collision.cc
  M lily/rest.cc
  M lily/slur-scoring.cc
  M lily/time-signature.cc
  M lily/vaticana-ligature.cc