[gnugo-devel] trevor_1_17.3

[Trevor Morris]

http://www.public32.com/games/go/trevor_1_17.3

 - take into account followup values if reverse_followup >= 1
 - try a little harder in attack_either
 - break_through_helper improved.
 
break_through_helper used to incorrectly give a WIN when there
was an easy defense (the problem was it didn't give O a chance
to back off trying to capture, and just return CUT rather than
WIN).  This fix reduces some matches in owl reading.