[feat] Simplify auto diff ceres
- Ceres internally squares the cost function residual.
- By now, the square of the residual is computed, then the sqrt and Ceres computes the square again afterwards.
- This MR changes the dimension of the residual (1D->3D) to avoid this behaviour.
- Some comments/names are updated to better fit the code behaviour.
- The gain is about 10% on LM optim step (5% on localization step for 3 iterations)
Edited by Julia Sanchez