Returns the last position of a given line. Lines are numbered starting with 0.
Calling this method may force the recalculation of location information if a maximum width is set for the editor, even if the editor currently has delayed refreshing (see refresh-delayed?). If the editor is not displayed and the editor has a maximum width, line breaks are calculated as for line-start-position.
See also paragraph-start-position, which operates on paragraphs (determined by explicit newline characters) instead of lines (determined by both explicit newline characters and automatic line-wrapping).
If there are fewer than line-1 lines, the end of the last line is returned. If line is less than 0, then the end of the first line is returned.
If the line ends with invisible items (such as a carriage return) and visible? is not #f, the first position before the invisible items is returned.