adds the POOL to box station

F in chat for dorms 7.

code/__DEFINES/pool.dm

@@ -0,0 +1,10 @@
+//TODO: move these to their own file
+#define POOL_FRIGID 1
+#define POOL_COOL 2
+#define POOL_NORMAL 3
+#define POOL_WARM 4
+#define POOL_SCALDING 5
+
+#define POOL_REAGENT_TICK_INTERVAL 5
+
+GLOBAL_LIST_INIT(blacklisted_pool_reagents, list("plasma"))