#16 Online Hints

[Ellery Blood]

Should include hints (good moves and bad moves
marked) to give beginner players hints. This should be
selectable through the preferences menu.

May have muliple levels of hints (e.g., 1. marking moves
that will result in an immediate loss with X's and
immediate wins with an O, 2. highlighting moves with a
high probability of winning).

[Ellery Blood]

Logged In: YES
user_id=839661

Should have a separate "hints" menu:

- mark winning placements
- mark losing placements
- mark losing choices
- mark "good" moves (maybe)

[Ellery Blood]

Logged In: YES
user_id=839661

The following tasks are necessary for this feature:

1) Addition of a "Hint" button
2) Support for placing x's on bad locations (placements)
3) Support fro placing x's on bad pieces (choices)
4) Identification of bad locations
5) Identification of bad pieces
6) Modification to DisplayScreen.cpp and state to indicate
that the x's are on.

Future Work:
1) Add hints to preferences to that hint button can be
enabled/disabled
2) Assuming I ever get around to implementing high-scores,
your change to achieve a high score would be removed if you
use a hint.