manual??? and refactoring

snake.c

@@ -244,7 +244,7 @@ static void update_snake(coordinate new_head, snake_action action) {
 static void *snake_move(void *arg) {
     struct timespec timer;
     timer.tv_sec = 0;
-    timer.tv_nsec = 250000000L;
+    timer.tv_nsec = 250000000L; // Snake moves every 0.25 seconds.
 
     while (rooster_vraag_toestand(GRID) == STATE_AAN_HET_SPELEN) {
         nanosleep(&timer, NULL);
@@ -311,6 +311,7 @@ static void *play_snake(void *arg) {
                 turn_snake(DIRECTION_RIGHT);
                 break;
             case KEY_BACKSPACE:
+            case KEY_ESCAPE:
                 rooster_zet_toestand(GRID, STATE_QUIT);
                 break;
         }
@@ -352,5 +353,5 @@ void snake(void) {
     pthread_mutex_destroy(&MUTEX);
 
     rooster_klaar(GRID);
-    graceful_exit();
+    graceful_exit(MESSAGE_LOCATION);
 }