Insert a new element to the string_list. The returned pointer can be
handy if you want to write something to the `util` pointer of the
- string_list_item containing the just added string.
+ string_list_item containing the just added string. If the given
+ string already exists the insertion will be skipped and the
+ pointer to the existing item returned.
Since this function uses xrealloc() (which die()s if it fails) if the
list needs to grow, it is safe not to check the pointer. I.e. you may