(Voverflow_newline_into_fringe): New variable.

(Voverflow_newline_into_fringe): New variable.
(IT_OVERFLOW_NEWLINE_INTO_FRINGE): New macro.
(move_it_in_display_line_to): Overflow newline into fringe for
rows that are exactly as wide as the window.
(up_arrow_bits, down_arrow_bits, first_line_bits, last_line_bits)
(filled_box_cursor_bits, hollow_box_cursor_bits, bar_cursor_bits)
(hbar_cursor_bits, hollow_square_bits): New fringe bitmaps.
(fringe_bitmaps): Add new bitmaps.
(draw_fringe_bitmap): Make extern.  Remove WHICH arg.
Select proper bitmap for cursor in fringe when appropriate.
Handle alignment of bitmap to top or bottom of row.
(draw_row_fringe_bitmaps): Don't select bitmaps here; that is now
done by update_window_fringes.
(update_window_fringes, draw_window_fringes): New functions.
(redisplay_internal): Call update_window_fringes in case only
cursor row is updated.
(redisplay_window): Call update_window_fringes.
Explicitly call draw_window_fringes if redisplay was done using
the current matrix or the overlay arrow is in the window.
(try_window_reusing_current_matrix): Mark scrolled rows for
fringe update (to update buffer-boundaries / scrolling icons).
(find_last_unchanged_at_beg_row): Handle exact width lines line
continued lines.
(display_line): Overflow newline into fringe for rows that are
exactly as wide as the window.  Don't append space for newline
in this case.
(notice_overwritten_cursor): Explicitly clear cursor bitmap
in fringe as if it had been overwritten.
(erase_phys_cursor): Erase cursor bitmap in fringe.
(syms_of_xdisp): Mark show-trailing-whitespace and
void-text-area-pointer as user options.
DEFVAR_LISP Voverflow_newline_into_fringe.  Enable by default.