Add built-in answer tones and automatic multiple-choice progression

ui.h

@@ -0,0 +1,11 @@
+#ifndef UI_H
+#define UI_H
+#include "quiz.h"
+void text(unsigned x,unsigned y,const char *s,U8 color);
+void frame(const char *label);
+void show_map(U8 state);
+U8 next_key(void);
+void release_keys(void);
+void close_input(void);
+extern unsigned entropy;
+#endif