SkeletonFitting fit leg position is now more eficient

When fit mid_pos_top_leg fail it saves the paw index and it gives it to
fit simple instead of calculating it again
Skeleton, added method to rotate a pair of bones but maintain the end position.
Skeleton added rotation method that maintains de aim.

With this new method the next bones are not perturbed when the previous ones
are being rotated.
Skeletoncontroller updated display paw