ConstructionSite: Remove unused function

It did not really disallow taking stuff out, so I removed it.

planet/Objects.ocd/Structures.ocd/ConstructionSite.ocd/Script.c

@@ -14,8 +14,6 @@ local is_constructing;
 
 // This should be recongnized as a container by the interaction menu independent of its category.
 public func IsContainer() { return !full_material; }
-// disallow taking stuff out
-public func RefuseTransfer(object toMove) { return true; } // TODO: this is not used by another function, is this a callback?
 // disallow site cancellation. Useful e.g. for sites that are pre-placed for a game goal
 public func MakeUncancellable() { no_cancel = true; return true; }