General refactor and minor improvements

spel.c

@@ -12,14 +12,18 @@
  */
 
 #include "grid_game_engine.h"
-#include "manual.h"
 #include "minigame_menu.h"
 
+/*
+ * Play minigame menu.
+ *
+ * Side effect:
+ * Minigame menu starts.
+ */
 int main(void) {
     init_engine();
 
     // Speel het spel.
-    // manual((coordinate){0,3});
     minigame_menu();
 
     cleanup_engine();