improving the transition between full-length and shortened stems.

improving the transition between full-length and shortened stems.

Now the change in length between regular stems (3.5 ss) and shortened stems (2.5 ss) is executed more gradually.

more flexible transition between regular and shortened stems

(BUGGED) Transition in stem length depends on staff radius and other things

cosmetic bugfix

Some bugs fixed with transition length

Combined commit: smooth transition between regular and shortened stems.

This is first solution with Han-Wen suggestions added.

transition code - stylistic changes suggested by Han-Wen