Do more aggressive pruning for some node types

This patch allows more aggressive futility/see based pruning for PV nodes with low delta and non-pv nodes.

Fixes some white space issues.

Passed STC
https://tests.stockfishchess.org/tests/view/61a5ed33d16c530b5dcc27cc
LLR: 2.95 (-2.94,2.94) <0.00,2.50>
Total: 182088 W: 47121 L: 46584 D: 88383
Ptnml(0-2): 551, 20687, 48037, 21212, 557

Passed LTC
https://tests.stockfishchess.org/tests/view/61a74dfdbd5c4360bcded0ac
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 87136 W: 22494 L: 22103 D: 42539
Ptnml(0-2): 38, 8918, 25272, 9295, 45

closes https://github.com/official-stockfish/Stockfish/pull/3828
closes https://github.com/official-stockfish/Stockfish/pull/3829

bench 4332259

src/misc.h

@@ -141,7 +141,7 @@ private:
 
 /// sigmoid(t, x0, y0, C, P, Q) implements a sigmoid-like function using only integers,
 /// with the following properties:
-/// 
+///
 ///  -  sigmoid is centered in (x0, y0)
 ///  -  sigmoid has amplitude [-P/Q , P/Q] instead of [-1 , +1]
 ///  -  limit is (y0 - P/Q) when t tends to -infinity