Initializes @iter with the “end iterator,” one past the last valid
character in the text buffer. If dereferenced with
gtk_text_iter_get_char(), the end iterator has a character value of 0.
The entire buffer lies in the range from the first position in
the buffer (call gtk_text_buffer_get_start_iter() to get
character position 0) to the end iterator.
Initializes @iter with the “end iterator,” one past the last valid character in the text buffer. If dereferenced with gtk_text_iter_get_char(), the end iterator has a character value of 0. The entire buffer lies in the range from the first position in the buffer (call gtk_text_buffer_get_start_iter() to get character position 0) to the end iterator.