bugfix: Cut node can become All node
No functional change, since the search behaves the same for All and Cut nodes (for now).
signature = 5908673
IID at every Cut node
And only when eval+Pawn >= beta at All node.

8000 games in 10"+0.1"
2000-1853-4147 [50.9%] LOS=99.1%

signature = 5900879