Bonus for restricting opponent's piece moves

STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 51883 W: 11297 L: 10915 D: 29671
http://tests.stockfishchess.org/tests/view/5bf1e2ee0ebc595e0ae3cacd

LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 15859 W: 2752 L: 2565 D: 10542
http://tests.stockfishchess.org/tests/view/5bf337980ebc5902bcecbf62

Notes:

(1) The bonus value has not been carefully tested, so it may be possible
to find slightly better values.

(2) Plan is to now try adding similar restriction for pawns. I wanted to
include that as part of this pull request, but I was advised to do it as
two separate pull requests. STC is currently running here, but may not add
enough value to pass green.

Bench: 3679086

src/pawns.cpp

@@ -221,7 +221,7 @@ Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
 
       int d = std::min(f, ~f);
       safety += ShelterStrength[d][ourRank];
-      safety -= (ourRank && (ourRank == theirRank - 1)) ? 66 * (theirRank == RANK_3) 
+      safety -= (ourRank && (ourRank == theirRank - 1)) ? 66 * (theirRank == RANK_3)
                                                         : UnblockedStorm[d][theirRank];
   }