Doxygenized MOM_remapping.F90

- Revised comments only.
  - No code changes other than to separate grouped declarations for
  subroutine arguments.
- Leading by example for issue #229. I took the extra five minutes after
  commit 7d9de97 to follow through - it actually took 20 minutes.
  - Although I deserve some 🍦 I'm 😪 so am packing it in
    for the night.
- No answer changes.