message: Use tostring wrapper to get string of the number not the __LINE__ ident
diff: /* debug printing macros */
  #define STRING(x) #x
  #define TOSTRING(x) STRING(x)
  -#define CODE_LOCATION __FILE__ " (" STRING(__LINE__) ")"
  +#define CODE_LOCATION __FILE__ " (" TOSTRING(__LINE__) ")"
  #define PING std::cout << CODE_LOCATION << ": " << __FUNCTION__ << std::endl
  #define PRINT(x) std::cout << STRING(x) << " = " << (x) << std::endl
  #define PRINT2(x,y) std::cout << STRING(x) << " = " << (x) << ", " << STRING(y) << " = " << (y) << std::endl
  