IKSolver now uses LMA inverse solver.
SkeletonController, added solver success check, deleted previous IKAN code
IKSolver, manually check result to fix some errors.

The iksolver would return sometimes a fail flag when it actually found the
solution.
SkeletonController, changed ik_chain to start with root node.

Insertion is less eficient but code in much more clear.
IKSolver changed argument position in solve_chain