Support more GTP commands

[amj]

in particular:

• final_score
• final_status_list

maybe some of the time commands to make the CGOS player a little more robust.

[amj]

If you're interested in digging into the code, final_score should be easy to implement, but final_status_list might be quite hard :)

[sethtroisi]

final_score the easy implementation is done. final_status_list is a larger work item.

[amj]

final_status_list is now doable with the output from benson's algorithm.