Retire KingDanger array

Rescales the king danger variables in evaluate_king() to
suppress the KingDanger[] array. This avoids the cost of
the memory accesses to the array and simplifies the non-linear
transformation used.

Full credits to "hxim" for the seminal idea and implementation,
see pull request #786.
https://github.com/official-stockfish/Stockfish/pull/786

Passed STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 9649 W: 1829 L: 1689 D: 6131

Passed LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 53494 W: 7254 L: 7178 D: 39062

Bench: 6116200

src/search.cpp

@@ -920,8 +920,8 @@ moves_loop: // When in check search starts from here
 
       // Step 13. Pruning at shallow depth
       if (  !rootNode
-         && !inCheck
-         &&  bestValue > VALUE_MATED_IN_MAX_PLY)
+          && !inCheck
+          &&  bestValue > VALUE_MATED_IN_MAX_PLY)
       {
           if (   !captureOrPromotion
               && !givesCheck