Slur collisions

[Chris Snyder]

During the course of engraving a fairly complex choral piece, I've run 
into quite a few slur bugs, including 307 (slur collision with tuplet 
bracket) and 379/586 (slur issues across line breaks).

Hoping to be able to fix some of the issues myself and learn about the 
internals of LilyPond, I started out trying to fix bug 307. As I learned 
more about the slur code, however, I realized that I was in way over my 
head. It appears to me that the problem is that slurs currently have no 
way of avoiding lines (such as a tuplet bracket), but instead focus on 
avoiding points (such as a fermata). It seems to me that adding 
line-avoidance would be a good idea, but I don't have the expertise and 
understanding of the code necessary to implement such a far-reaching change.

I've benefited greatly from LilyPond's excellent engraving capabilities. 
I'd like to give back - and it seems that the slur code is one of the 
areas of greatest need of attention. Since I do not have the expertise 
to do this, I'm willing to sponsor some work here - especially dealing 
with the issues named above.

Would anyone be willing to tackle this? If so, what do you think would 
be a reasonable sponsorship amount?

Thanks for producing such an excellent piece of software. I'd like to 
contribute, but feel that I can better contribute finances than code at 
this point.