Fix play past threefold

[wdotmathree]

Elo   | 3.35 +- 4.02 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=32MB
LLR   | 2.90 (-2.25, 2.89) [-5.00, 0.00]
Games | N: 7894 W: 1843 L: 1767 D: 4284
Penta | [28, 929, 1965, 989, 36]

https://ob.int0x80.ca/test/261/

Bench: 5092271

[kevlu8]

I will have you know I spent a precious 2 minutes copying over the vector code to largevector, and as such my feelings are very hurt by your deletion of it.

[wdotmathree]

Good.

[wdotmathree]

Damn no approval :(

[kevlu8]

You're approved