Include bishop protection in king Danger evaluation. #2118

Same idea as fisherman's knight protection.

passed STC
LLR: 2.96 (-2.94,2.94) [0.50,4.50]
Total: 17133 W: 3952 L: 3701 D: 9480 
http://tests.stockfishchess.org/tests/view/5cc3550b0ebc5925cf02dada

passed LTC
LLR: 2.95 (-2.94,2.94) [0.00,3.50]
Total: 37316 W: 6470 L: 6188 D: 24658 
http://tests.stockfishchess.org/tests/view/5cc3721d0ebc5925cf02dc90

Looking at this 2 ideas being recent clean elo gainers I have a feeling that we can add also rook and queen protection bonuses or overall move this stuff in pieces loop in the same way as we do pieces attacking bonuses on their kingring... :) Thx fisherman for original idea.

Bench 3429173

src/evaluate.cpp

@@ -467,12 +467,13 @@ namespace {
                  +  69 * kingAttacksCount[Them]
                  + 185 * popcount(kingRing[Us] & weak)
                  - 100 * bool(attackedBy[Us][KNIGHT] & attackedBy[Us][KING])
+                 -  35 * bool(attackedBy[Us][BISHOP] & attackedBy[Us][KING])
                  + 150 * popcount(pos.blockers_for_king(Us) | unsafeChecks)
                  - 873 * !pos.count<QUEEN>(Them)
                  -   6 * mg_value(score) / 8
                  +       mg_value(mobility[Them] - mobility[Us])
                  +   5 * kingFlankAttacks * kingFlankAttacks / 16
-                 -   15;
+                 -   7;
 
     // Transform the kingDanger units into a Score, and subtract it from the evaluation
     if (kingDanger > 100)