hrmm, just checked changelog, and you're right, it isn't listed.. but it prolly wasn't because of backward compatibility, so you really don't need to..
/* Converts number to string. */
/* Returns converted string to number. */
native str_to_num(const string);
the function names were changed, but backwards compatibility was added for it in amxmod.inc:
stock strtonum(const string)
But as for a general list of all Natives/Forwards/Stocks that would defintely be nice!! (I think it's coming with 0.2 version)