cleans up trainer battle scripts

* adds battle type macros
* adds `trainerbattle_normal` macro
* adds `trainerbattle_double` macro
* adds rematch macros
* adds no intro macro

src/battle_setup.c

@@ -1,6 +1,7 @@
 #include "global.h"
 #include "constants/trainers.h"
 #include "battle.h"
+#include "constants/battle_setup.h"
 #include "battle_setup.h"
 #include "battle_transition.h"
 #include "main.h"