Enhancement: support modern-style ties

[Simon Albrecht]

Hello,

in many scores of modern music, ties are not drawn to their full extent, 
but (speaking in lilypond terms :-)) only as a RepeatTie on the second 
chord (example attached), eventually also with a LaissezVibrerTie on the 
first chord. This is often necessary because full-length ties would 
produce very crowded output, be difficult or impossible to place.
Although it’s possible to produce this output with current Lily through 
q\laissezVibrer q\repeatTie, it should rather be coded as usually with 
q~ q and then modified through an override on Tie.
I suggest adding a 'style property with the following possible values:
'full-length (default)
'modern-single (or 'modern)
'modern-double

Yours,
Simon

messiaen-ties.jpg
Description: JPEG image