Goldfish v1.2: Check extension.

This probably hurts the benchmark quite a bit, but testing shows an
improvement in strength.

   # PLAYER           :  RATING  POINTS  PLAYED   (%)
   1 goldfish-v1.2    :  2349.7    17.0      30    57
   2 goldfish-v1.1    :  2302.7    31.5      62    51
   3 goldfish-v1.0    :  2247.5    13.5      32    42

Author: bsamseth

CMakeLists.txt

@@ -17,7 +17,7 @@ enable_language(CXX)
 # by including "projectmeta.hpp" in the source. 
 # See projectmeta.hpp.in for some more details.
 set(PROJECT_VERSION_MAJOR 1)
-set(PROJECT_VERSION_MINOR 1)
+set(PROJECT_VERSION_MINOR 2)
 
 
 # Include stuff. No change needed.

src/search.cpp

@@ -411,6 +411,9 @@ int Search::search(int depth, int alpha, int beta, int ply) {
         return Value::DRAW;
     }
 
+    if (position.is_check())
+        depth += 1;
+
     // Initialize
     int best_value = -Value::INFINITE;
     int searched_moves = 0;