set_implicit_trailing_newline
Description:
Sets whether the this has an implicit trailing newline.
If an explicit trailing newline is present in a [class@Gtk.TextBuffer], [class@Gtk.TextView] shows it as an empty line. This is generally not what the user expects.
If implicit_trailing_newline is true (the default value):  - when a [class@FileLoader] loads the
       content of a file into the this,  the trailing newline (if present in the file) is not inserted into the  
      this.  - when a [class@FileSaver] saves the content of the this into a file,
       a  trailing newline is added to the file.
On the other hand, if implicit_trailing_newline is false, the file's content is not modified 
      when loaded into the this, and the this's content is not modified when saved
       into a file.
Parameters:
| this | a Buffer. | 
| implicit_trailing_newline | the new value. |