Rewrite the way application exits

Centralize in a single object all the global resources
management and avoid a bunch of sparse exit() calls.

This is more reliable and clean and more stick to C++ coding
practices.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/evaluate.cpp

@@ -505,6 +505,8 @@ void quit_eval() {
   {
       delete PawnTable[i];
       delete MaterialTable[i];
+      PawnTable[i] = NULL;
+      MaterialTable[i] = NULL;
   }
 }