[Bug-gnubg] new cube rating computation

[max-d]

hi,
The new cube rating computation does not look fair ...
i can't agree i'm a beginner cube user  just because of this wrong take !
3 point match


Move number 11: O doubles to 2

 GNU Backgammon  Position ID: bJ2DAyDMngcHAA
                 Match ID   : MBlgAAAAAAAA
 +12-11-10--9--8--7-------6--5--4--3--2--1-+     O: gnubg
 | X           O    |   | O  O     O     X |     0 points
 | X           O    |   | O  O     O       |
 | X           O    |   | O                |
 |             O    |   | O                |
 |                  |   |                  |
^|                  |BAR|                  |
 |                  |   |                  |
 |                  |   |                  |
 | O           X    |   | X                |
 | O           X    |   | X     X  X       |     Cube offered at 2
 | O           X    |   | X  X  X  X       |     0 points
 +13-14-15-16-17-18------19-20-21-22-23-24-+     X: user

* user accepts

Alert: wrong take ( -0,53%)! [doubtful]
Cube analysis
2-ply cubeless MWC  55,67%
  0,729 0,108 0,001 - 0,271 0,036 0,001
1. Double, pass         60,00%
2. Double, take         60,53%  ( +0,53%)
3. No double            58,88%  ( -1,12%)
Proper cube action: Double, pass

md.