fix bug in physics.sml where player/enemy would drop below continuously past multiple platforms even if they intended to drop below platforms only once (fixed by setting yAxis to 'FALLING' if there are no collisions at all and player is in DROP_BELOW_PLATFORMS state)

fcore/enemy-behaviour.sml

@@ -1,4 +1,4 @@
-structure EnemyBehaviour =
+1tructure EnemyBehaviour =
 struct
   open GameType
 
@@ -143,6 +143,22 @@ struct
   fun hasVisted (find, visited) =
     helpHasVisited (0, Char.chr find, visited)
 
+  fun isBetween (p1, check, p2) = check >= p1 andalso check <= p2
+
+  fun isReachableFromBottom (prevPlat: platform, currentPlat: platform) =
+    let
+      val {x = prevX, y = prevY, width = prevWidth, ...} = prevPlat
+      val {x = curX, y = curY, width = curWidth, ...} = currentPlat
+
+      val prevFinishX = prevX + prevWidth
+      val curFinishX = curX + curWidth
+    in
+      (isBetween (prevX, curX, prevFinishX)
+       orelse
+       isBetween (prevX, curFinishX, prevFinishX)
+       andalso prevY + Constants.jumpLimit >= curY)
+    end
+
   fun isReachableFromLeft (prevPlat, currentPlat) =
     (* prev = right/from, current = left/to *)
     let