Start towards fixing the tie / time signature collision problem. (issue4528061)

[mtsolo]

Reviewers: ,

Message:
I recently tried to redo a score such that my ties did not intersect
with time signatures.  I got it to work with buggy code and a lot of
kludges, so I thought I'd propose a modified version with less kludges
(though still buggy code).

The code is getting the bezier t points wrong in Tie::make_keep_regions,
which makes the X-extent of the two bezier extracts wrong.  It does not
do Y-extent checking yet, but I'll sort that out once I get the X-extent
stuff right.  Below is a test file I've been using which shows both
ok(ish) and bad results.  I also have a comment and a pretty print in
the code to help anyone willing to take a stab at why the X-extents are
slightly off.

Any help with the X-extent problem would be appreciated!  This code is
obviously generalizable outside of ties and I'll get to that in due
time, but first I want to nail the X-extent problem.

\version "2.15.0"

% bad
\relative c'' {
  \tieUp
  a1 ~ \time 8/8 a1 |
}

% ok
\relative c'' {
  \time 4/4 r2... d16 ~ \time 8/8 d16 r2... |
}

% ok
\relative c'' {
  \tieUp
  \time 8/8 r2... g16 ~ \time 4/4 g16 r2... |
}

% ok
\relative c'' {
  \tieUp
  \time 8/8 r2.. g8 ~ \time 4/4 g8 r2.. |
}

% ok
\relative c'' {
  \tieUp
  \time 8/8 r2. g4 ~ \time 4/4 g4 r2. |
}

% bad
\relative c'' {
  << { \time 8/8 r2. g4 ~ \time 4/4 g4 r2. } \\ { \repeat unfold 64 {
d32 \noBreak } } >>
}


Description:
Start towards fixing the tie / time signature collision problem.

Please review this at http://codereview.appspot.com/4528061/

Affected files:
  M lily/arpeggio.cc
  M lily/include/lookup.hh
  M lily/include/tie.hh
  M lily/lookup.cc
  M lily/slur.cc
  A lily/tie-collision-engraver.cc
  M lily/tie-engraver.cc
  M lily/tie.cc
  M ly/engraver-init.ly
  M scm/define-grob-properties.scm
  M scm/define-grobs.scm