tools/atrf-rssi/: added menu for regulation area selection

- gui.c (area_off, gui): don't show a regulation area by default
- letter.h, letter.c: drawing of limited character set
- Makefile (OBJS_host, OBJS_ben_jlime): added letter.o
- gui.c (print, area_selector, gui): show regulation area selector

tools/atrf-rssi/letter.h

@@ -0,0 +1,25 @@
+/*
+ * atrf-rssi/letter.h - Draw 7 segment style letters
+ *
+ * Written 2011 by Werner Almesberger
+ * Copyright 2011 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#ifndef LETTER_H
+#define LETTER_H
+
+#include <stdint.h>
+
+#include "SDL.h"
+
+
+void letter(SDL_Surface *s, char c, int x0, int x1, int y0, int ym, int y1,
+    uint32_t fg);
+
+#endif /* !LETTER_H */