Fix selective import

[jcp19]

NOT READY FOR REVIEW

[jcp19]

Also, modify TypeInfoImpl.scala after merging the PR for the preserves keyword to include the nodes refered in preserves clauses.

private def addTransitiveDeps(r: SymbolTable.Regular): Unit = {
    def checkedNodesFromFuncSpec(spec: PFunctionSpec): Vector[PNode] =
      spec.pres ++ spec.preserves ++ spec.posts ++ (spec.pres ++ spec.preserves ++ spec.posts).flatMap(_.subNodes)
        // TODO: check why this causes node not in tree exception
        // (try { (spec.pres ++ spec.posts) flatMap allChildren } catch { case e => Seq.empty })