- "CONSTRAINT_IK_AUTO" flag for targetless IK constraints was being
set in the wrong place. This is for the IK constraint data's flag, not
the generic constraint's flag
- Converting stack var "targetless" from type bConstraint to
bKinematicConstraint (i.e. constraint baseclass -> specialised data),
since it was only used in one place with a cast used there.
- When using targetless IK with no specified chain length, bone
rotation locks are taken into account too, saving a bit of extra setup
work