make bool to int cast explicit

alib2std/src/extensions/compare.hpp

@@ -117,7 +117,7 @@ struct compare < bool > {
 	 * \return negative value of left < right, positive value if left > right, zero if left == right
 	 */
 	int operator ( ) ( bool first, bool second ) const {
-		return first - second;
+		return static_cast < int > ( first ) - static_cast < int > ( second );
 	}
 };