Subject truncated incorrectly

Following on from the discussion in #1665304: SQL error if subject too long.

I have tried this patch on my site and it works. It limits the number of characters in the subject to 64 rather than 29, and correctly adds the dots - the fourth argument to truncate_utf8() needs to be TRUE. I also removed the if statement since truncate_uft8() has a similar if statement in it using drupal_strlen() which correctly handles multibyte strings.