Stem-attachment

[Rune Zedeler]

Thanks for the new stem-attachment.
It does not quite work, though.
The x-part looks correct, but the y-part gets wrong. - the value gets
multiplied by a too small number.
Take a look at input/regression/note-head-style.ly
The crosses are not connected to the stem at the bottom - as they should
be according to output-lib.scm
Another problem arises when noteheads with different x-attachment are
put on the same stem. Seems like the x-attachment from the first
notehead is used by all the heads.

-Rune