insert_sorted_iter
Description:
Like insert_sorted, but uses a SequenceIterCompareFunc instead of a CompareDataFunc as the compare function.
iter_cmp is called with two iterators pointing into this. It should return 0 if the iterators 
      are equal, a negative value if the first iterator comes before the second, and a positive value if the second iterator comes before the first.
    
Note that when adding a large amount of data to a Sequence, it is more efficient to do unsorted insertions and then call sort or sort_iter.
Example: Insert sorted, iter:
public static int main (string[] args) {
	Sequence<string> seq = new Sequence<string> ();
	seq.append ("1. Lorem");
	seq.append ("2. ipsum");
	seq.append ("4. sit");
	seq.append ("5. amet");
	seq.insert_sorted_iter ("3. dolor", (a, b) => {
		return strcmp (a.get (), b.get ());
	});
	// Output:
	//  ``1. Lorem``
	//  ``2. ipsum``
	//  ``3. dolor``
	//  ``4. sit``
	//  ``5. amet``
	seq.foreach ((item) => {
		print ("%s\n", item);
	});
	return 0;
}
    
    valac --pkg glib-2.0 GLib.Sequence.insert_sorted_iter.vala
    Parameters:
| this | 
           a Sequence  | 
      
| data | 
           data for the new item  | 
      
| iter_cmp | 
           the function used to compare iterators in the sequence  | 
      
| cmp_data | 
           user data passed to   | 
      
Returns:
| 
           a SequenceIter pointing to the new item  |