fix #2316: small ties

Two main strategies employed:

1) Move ties in simple case to overlap noteheads more.  I am conservative here - increasing only from 15% to 35% even though Gould actually recommends 50%.  But Sibelius and LilyPond both seem more in line with what I've done.

2) Add new style parameter minTieLength, add space as necessary in front of second note of tie to ensure tie is at least that long.  This code should have no impact on ties that were not already too short.

I have set the default minTieLength at 1.0sp, which seems conservative but effective.  I didn't reduce this for read114, but we might consider it for better compatibility.