(redisplay_internal): Use scan_newline.

(redisplay_internal): Use scan_newline.
(try_window_id): Use scan_newline.
(display_text_line): Use scan_newline.

(pos_tab_indent): Moved from indent,c.  Now static.
Take POS in bytes and chars.  Callers changed.

(redisplay_window): Handle byte and char positions.
(try_window): Don't move W->start if it's already at right place.

(display_count_lines): Several changes in args.
Do the work directly.
(display_scan_buffer): Function deleted.
(decode_mode_spec): Pass new arg.
(message_log_check_duplicate): Take charpos and bytepos args.
(message_dolog): Use markers to update old PT, BEGV, ZV.
Use scan_newline.  Handle positions in bytes and chars.

(try_window): Pass bytepos to and from display_text_line.
(try_window_id): Likewise.  Use byte pos as well as charpos.
(redisplay_internal): Handle bytepos for tlbufpos.

(message): Cast last arg to doprnt.