Add a level of indirection to terminal characteristics.

Add a level of indirection to terminal characteristics.

* src/termchar.h (struct terminal): New struct.
(must_write_spaces, min_padding_speed, line_ins_del_ok)
(char_ins_del_ok, scroll_region_ok, scroll_region_cost)
(memory_below_frame, fast_clear_end_of_line): Moved to struct
terminal.
(current_terminal): New variable.
(CURRENT_TERMINAL, TERMINAL_*): New accessor macros.
(min_padding_speed, dont_calculate_costs): Commented out (unused).

* src/term.c (_current_terminal): New variable.  Will be removed when
true multi-tty support is implemented.

* src/termopts.h (no_redraw_on_reenter): Moved here.

* src/term.c (set_terminal_window, ins_del_lines, calculate_costs)
(term_init): Use the accessor macros for terminal characteristics.
* src/dispnew.c (line_hash_code, line_draw_cost)
(direct_output_for_insert, update_frame_1, scrolling)
(update_frame_line): Ditto.
* src/macterm.c (mac_initialize): Ditto.
* src/msdos.c (internal_terminal_init): Ditto.
* src/scroll.c (calculate_scrolling, calculate_direct_scrolling)
(scrolling_1, scroll_cost): Ditto.
* src/sysdep.c (hft_init): Ditto.
* src/w32term.c (w32_initialize): Ditto.
* src/xdisp.c (try_window_id): Ditto.
* src/xterm.c (x_initialize): Ditto.

* etc/TODO: Add pointer to my tla archive.

git-archimport-id: lorentey@elte.hu--2004/emacs--multi-tty--0--patch-1