Blender Git Loki

Better defaults for stretch stiffness and damping.

The strong stretch forces lead to awkward lengthening of segments when
the damping factor is too high.

In fact, in a natural hair strand the stretching usually means the hair
itself is curly and stretches as a helical spring. In that case
the damping is quite small compared to the stiffness, and little energy
is lost to the stretching (the hair becomes "bouncy"). When the hair is
very stiff the damping should also be small in order to avoid extreme
forces resulting from the hair root location constraint.