Blender Git Loki

New hair child options:
* Renamed children to "simple" and "interpolated" as this is
easier to explain and more descriptive than "from particles"
and "from faces".
* Also shuffled the child ui around a bit to make it clearer.
* Child seed parameter allows to change the seed for children
independent of the main seed value.
* Long hair mode for interpolated children:
- Making even haircuts was impossible before as the child
strand lengths were even, but their root coordinates were
not similar in relation to the parent strands.
- The "long hair" option uses the tips of the parent strands
to calculate the child strand tips.
* Hair parting options:
- Hair parting can now be calculated dynamically on the fly
when in 2.49 there was a cumbersome way of using emitter mesh
seams to define parting lines.
- For long hair parting can be created by a tip distance/root
distance threshold. For example setting the minimum threshold
to 2.0 creates partings between children belonging to parents
with tip distance of three times the root distance
((1+2)*root distance).
- For short hair the parting thresholds are used as angles
between the root directions.
* New kink parameters:
- Kink flatness calculates kink into a shape that would have
been achieved with an actual curling iron.
- Kink amplitude clump determines how much the main clump value
effects the kink amplitude.
- The beginning of kink is now smoothed to make the hair look
more natural close to the roots.
* Some bugs fixed along the way too:
- Child parent's were not determined correctly in some cases.
- Children didn't always look correct in particle mode.
- Changing child parameters caused actual particles to be
recalculated.
* Also cleaned up some deprecated code.

All in all there should be no real changes to how old files look
(except perhaps a bit better!), but the new options should make
hair/fur creation a bit more enjoyable. I'll try to make a video
demonstrating the new stuff shortly.