fix compile errors after previous commit (which involved reimplementing the quad tree to eliminate the possibility of a class of bugs I was experiencing; the problem was that the quad bounds were being passed recursively in different functions, but the long argument list in these functions made it difficult to see where the mismatch was)

fcore/wall.sml

@@ -6,13 +6,17 @@ struct
     else
       let
         val {id, x, y, width, height} = Vector.sub (wallVec, pos)
-        val acc = QuadHelp.insert
-          (x, y, width, height, id, acc)
+        val acc = QuadTree.insert (x, y, width, height, id, acc)
       in
         helpGenerateTree (pos + 1, wallVec, acc)
       end
 
-  fun generateTree wallVec = helpGenerateTree (0, wallVec, QuadTree.empty)
+  fun generateTree wallVec =
+    helpGenerateTree
+      ( 0
+      , wallVec
+      , QuadTree.create (Constants.worldWidth, Constants.worldHeight)
+      )
 
   fun helpGetDrawVecWider
     (pos, wallVec, acc, winWidth, winHeight, ratio, yOffset) =