Fix NxN scan mode for lcu_get_final_cost.

- Scan mode was always selected according to the first PU mode.
Change cabac debug statements to show information better.

- Show the number of bits when encoding multiple bins. I would like just the
  bits them selves in string form, but that's too much trouble for this.

- Print then as unsigned and coerce them to unsigned, as they are going
  get coerced to unsigned by the function call anyway.

- Change state to be less verbose.
Update the names of some bins to the current spec.

- Helps with debugging.