Simplify Away Quadruple Extension
Passed non-regression VVLTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 90792 W: 23155 L: 23018 D: 44619
Ptnml(0-2): 6, 8406, 28432, 8549, 3
https://tests.stockfishchess.org/tests/view/664ffa4ca86388d5e27d8e7a
Passed non-regression VLTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 288136 W: 72608 L: 72659 D: 142869
Ptnml(0-2): 38, 30258, 83525, 30211, 36
https://tests.stockfishchess.org/tests/view/66551609a86388d5e27db9ae
closes https://github.com/official-stockfish/Stockfish/pull/5293
bench 1501735