* tuiGeneralWin.c (boxWin): Use the tui configuration variables.
* tuiWin.h: Declare the new variables.
* tuiWin.c (_initialize_tuiWin): Create TUI configuration variables.
(tui_update_variables): New function.
(translate): New function.
(tui_border_kind_enums, tui_border_mode_enums): New tables.
(tui_border_mode_translate): New table.
(tui_border_kind_translate_*): New tables.
(tui_active_border_mode): New variables.
(tui_border_*): New variables.