Clean up:

Clean up:
- ANSIfy function definitions.
- Constify where appropriate and remove `auto' declarations.
- Normalize whitespace and placement of braces.
- Parentheses around arguments to sizeof.
- Explicitly test against NUL character.
- Use curses functions instead of accessing internal members of the
  WINDOW structure.
- Eliminate a convoluted and unnecessary goto.
- Raise WARNS to 6.

Brought-to-my-attention-by: my CPSC 213 lab assignment