first and second if second comes before
first in the buffer. That is, ensures that first and second are
in sequence. Most text buffer functions that take a range call this
automatically on your behalf, so there's no real reason to call it yourself
in those cases. There are some exceptions, such as gtkTextIterInRange,
that expect a pre-sorted range.gtkTextIterOrder(object, second)objectsecondGtkTextIter