Using minimumSplitDepth = 5 seems to be the best compromise in the
current SMP implementation
STC, 11 threads:
ELO: 14.87 +-4.1 (95%) LOS: 100.0%
Total: 8509 W: 1497 L: 1133 D: 5879
STC, 4 threads:
ELO: 0.30 +-2.8 (95%) LOS: 58.2%
Total: 20000 W: 3365 L: 3348 D: 13287
STC, 2 threads:
ELO: -1.02 +-2.0 (95%) LOS: 16.4%
Total: 40000 W: 7087 L: 7204 D: 25709
Resolves #324