Fix vertical lines in Putty with UTF-8 graphics

Putty doesn't show VT100 line drawing characters in UTF-8 mode by
default.

Use Unicode drawing characters in UTF-8 mode for the vertical display
separator and the line number separator.

Closes #981

src/display.c

@@ -187,11 +187,30 @@ static void
 redraw_display_separator(bool clear)
 {
 	if (display_sep) {
-		chtype separator = opt_line_graphics ? ACS_VLINE : '|';
+		chtype separator;
+
+		switch (opt_line_graphics) {
+		case GRAPHIC_ASCII:
+			separator = '|';
+			break;
+		case GRAPHIC_DEFAULT:
+			separator = ACS_VLINE;
+			break;
+		default:
+			separator = ' ';
+			break;
+		}
 
 		if (clear)
 			wclear(display_sep);
 		wbkgd(display_sep, separator + get_line_attr(NULL, LINE_TITLE_BLUR));
+
+		if (opt_line_graphics == GRAPHIC_UTF_8) {
+			int lineno = 0;
+
+			while (mvwaddstr(display_sep, lineno++, 0, "│") == OK);
+		}
+
 		wnoutrefresh(display_sep);
 	}
 }

src/draw.c

@@ -314,7 +314,6 @@ draw_lineno_custom(struct view *view, struct view_column *column, unsigned int l
 	unsigned long digits3 = MIN(9,MAX(3,column->width));
 	int max = MIN(VIEW_MAX_LEN(view), digits3);
 	char *text = NULL;
-	chtype separator = opt_line_graphics ? ACS_VLINE : '|';
 	struct line_number_options *opts = &column->opt.line_number;
 	int interval = opts->interval > 0 ? opts->interval : 5;
 
@@ -332,7 +331,13 @@ draw_lineno_custom(struct view *view, struct view_column *column, unsigned int l
 		draw_chars(view, LINE_LINE_NUMBER, text, -1, max, true);
 	else
 		draw_space(view, LINE_LINE_NUMBER, max, digits3);
-	return draw_graphic(view, LINE_DEFAULT, &separator, 1, true);
+
+	if (opt_line_graphics == GRAPHIC_UTF_8)
+		return draw_chars(view, LINE_DEFAULT, "│ ", -1, 2, false);
+	else {
+		chtype separator = (opt_line_graphics == GRAPHIC_DEFAULT) ? ACS_VLINE : '|';
+		return draw_graphic(view, LINE_DEFAULT, &separator, 1, true);
+	}
 }
 
 bool