Does better polynomial calculations for avoid objects. (issue4860042)

[mtsolo]

Reviewers: ,

Message:
Hey all,

My summer of Lily plugs along with a fix for Issue 1328.  It also
generally cleans up a lot of little collisions in the regtests between
slurs and articulations.

Passes regtests.

Cheers,
MS

Description:
Does better polynomial calculations for avoid objects.

Please review this at http://codereview.appspot.com/4860042/

Affected files:
  M flower/include/polynomial.hh
  M flower/polynomial.cc
  A input/regression/slur-avoid.ly
  M lily/bezier.cc
  M lily/include/bezier.hh
  M lily/slur.cc
  M scm/define-grobs.scm
  M scm/script.scm