Setting a :parent in the opts should not break reaction handling

[dfrese]

Currently, a 'reaction' with an explicit target component, can stop working when :parent is set in the opts. But the :parent should only affect reactions that use :parent as the target:

In this test, the app-state change is silently lost:

(deftest parent-reaction-test
  (let [c1 (reacl/class "child" this state []
                        render (dom/div)
                        handle-message
                        (fn [msg]
                          (reacl/return :app-state msg)))
        received (atom nil)
        p1 (reacl/class "parent" this state [gparent]
                        render (c1 (reacl/opt :parent gparent
                                              :reaction (reacl/reaction this identity))
                                   state)
                        handle-message
                        (fn [msg]
                          (reset! received msg)
                          (reacl/return :app-state msg)))
        g1 (reacl/class "grandparent" this []
                        local-state [state nil]
                        render (p1 state this))

        c (tu/mount g1)]
    (tu/send-message! (xpath/select c (xpath/>> ** c1))
                      :test)
    (is (= @received :test))))